Class: EditField

• Inheritance
• Description
• Related information
• Class protocol
  • defaults
• Instance protocol
  • accepting
  • accessing-behavior
  • accessing-contents
  • accessing-look
  • cursor drawing
  • cursor movement
  • drag & drop
  • editing
  • event handling
  • focus handling
  • help
  • initialization & release
  • menu actions
  • native widget support
  • private
  • queries
  • realization
  • scrolling
  • selections
• Examples

Inheritance:

   Object
   |
   +--GraphicsMedium
      |
      +--DisplaySurface
         |
         +--SimpleView
            |
            +--View
               |
               +--ListView
                  |
                  +--TextView
                     |
                     +--EditTextView
                        |
                        +--EditField
                           |
                           +--EditFieldWithCompletion
                           |
                           +--FilenameEditField

Package:

stx:libwidg

Category:

Views-Text

Version:

rev: 1.281 date: 2019/02/12 09:28:59

user: stefan

file: EditField.st directory: libwidg

module: stx stc-classLibrary: libwidg

Author:

Claus Gittinger

Description:

an editable text-field. Realized by using an EditTextView,
and forcing its size to 1 line - disabling cursor movement
in the vertical direction.

Basically, an editField is an editor for a single line text,
and provides the usual access protocol as defined in its superClasses
(especially: #contents / #contents:).

The above underlying internal mechanism can be used for fields which
are passive; i.e. into which text can be entered and the value (string)
is extracted actively by someone else.

accepting:
  The opposite way to use editFields is to connect them to a model
  and let the field notify changes to it.
  This notification is called ``accepting''.
  Unless accepted, the models value is not updated from the editFields contents
  this default is the normal operation and way things should work, since most
  uses of editFields are not interested in every individual change
  (i.e. getting each keyStroke when a long number is entered).
  The default behavior is to ``accept'' when either return or a cursorUp/Down
  key is pressed in a field.
  However, the field can setup to accept/not accept on leave, on return
  or on each individual key input.
  See the method's #acceptOnLeave: / #acceptOnReturn: / #immediateAccept.

  In addition, the set of keys which are considered ``leaveKeys'' can be
  specified by #leaveKeys: (in case you need keys other than Return, CursorUp/Down).

models value vs. field contents:
  Although the field internally keeps its contents as some string object,
  the application may prefer to think of numbers, floats, yes/no values etc.
  To support this, a converter may defined, which is responsible for conversion of
  strings to/from the models domain value.
  If present (i.e. nonNil), the converter is asked to convert a string to the models
  domain with #readValueFrom:aString and vice versa, a value to a string by #printStringFor:.
  The PrintConverter class already provides a number of standard conversions, see the examples.
  To access a converted value directly (i.e. not via the model), use #editValue.

grouping:
  Individual fields do not know about being included in a group. This must be arranged on the
  outside, by placing multiple fields into an EnterFieldGroup.
  This groupObject keeps a reference to one active field, and forwards input from any other
  field to the active one. Also have a look at the examples for this.

input completion:
  To support input completion (i.e. filename completion, classname completion etc.),
  a completionBlock can be defined which (if non-nil) is evaluated when the completion-key
  is pressed and its value is taken as the new field-contents. 
  The physical completion-key is the Tab key (this one cannot be defined by
  the keyboardTranslation mechanism, since that would disable the Tab-key on regular text views.



[Instance variables:]

  leaveAction    <Block | nil>              if non-nil, this is evaluated with
                                            the key (#Return, #CursorUp etc.) when
                                            the field is left via keyboard keys.
                                            (fieldGroups use this to decide which
                                             field has to be enabled next)

  enabled        <Boolean>                  if false, input is ignored.

  clickAction    <Block | nil>              action performed if the field is
                                            clicked upon.
                                            (this is used by the group to
                                             set the active field to the clicked upon field)

  crAction       <Block | nil>              if non-nil, keyboard input of a cr are not
                                            handled specially, instead this block is evaluated
                                            (however, this block can perform additional checks and send
                                             a #accept then)

  tabAction      <Block | nil>              if non-nil, keyboard input of a tab character
                                            is not entered into the text, instead this block
                                            is evaluated. Also, no input completion is performed if
                                            tabAction is nonNil.

  converter      <PrintConverter | nil>     if non-nil, this is supposed to convert between
                                            the object and its printed representation and vice versa.
                                            Defaults to nil i.e. assume that strings are edited.

  leaveKeys      <Collection>               keys which are interpreted as 'leaving the field'

  immediateAccept   <Boolean>               if true, every change of the text is immediately
                                            forwarded to the model/acceptBlock. If false,
                                            the changed value is only stored in the model
                                            if the field is left or accepted.
                                            Default is false.

  acceptOnLeave  <Boolean>                  if true, leaving the field (via cursor keys)
                                            automatically accepts the value into the model.
                                            Default is true.

  acceptOnReturn <Boolean>                  if true, leaving the field via return
                                            automatically accepts the value into the model.
                                            Default is true.

  acceptOnTab    <Boolean>                  if true, the Tab key accepts and leaves the field.
                                            If false, Tabs are entered into the contents field like
                                            ordinary non-control keys.
                                            AcceptOnTab is ignored if the entryCompletion block is nonNil.
                                            Default is true.

  lengthLimit    <Number>                   the max. number of allowed characters

  entryCompletionBlock <BlockOrNil>         if non-nil, this is evaluated to complete the entry
                                            when <entryCompletionCharacter> is pressed.
                                            Entry completion is used with Filenamefields or in the
                                            browser for classname/selector completion.
                                            Setting a nonNil entryCompletion disables acceptOnTab.

  entryCompletionCharacter <CharacterOrNil> if non-nil AND entryCompletionBlock is nonNil, that one
                                            is evaluated for completion. Typically used to complete
                                            a fileName (also, classNames in the browser)
                                            Default is #Tab.

  passwordCharacter     <CharacterOrNil>    if non-nil, typed input is replaced by this character
                                            for display. Used for secret-input fields (such as password entry).
                                            Default is nil.

Related information:

    DialogBox
    EnterFieldGroup
    EnterBox
    EnterBox2
    FilenameEditField
    EditTextView

Class protocol:

 defaultBorderColor

 defaultBorderWidth

 defaultLeaveKeys

return the set of keys which are taken as leave-keys.
If the field is in an enterFieldGroup, all leave keys will be
forwarded to the group and possible step to the next/previous field.
Also, if acceptOnLeave is true, leave keys will store the current
value into their model (if any)

 defaultLevel

 defaultNumberOfLines

the number of lines in the field

 updateStyleCache

extract values from the styleSheet and cache them in class variables

usage example(s):

self updateStyleCache

Instance protocol:

 accept

accept the current contents by executing the accept-action and/or
changeMessage.
Do this only if the contents of the EditField differs
from the printed representation of the model.

 acceptIfUnchanged

return the acceptIfUnchanged flag setting.
if set (the default), an accept notification is sent on accept,
even if the fields value is the same. If cleared,
the notification is suppressed, if the fields contents is the same.

 acceptIfUnchanged: aBoolean

if set (the default), an accept notification is sent on accept,
even if the fields value is the same. If cleared,
the notification is suppressed, if the fields contents is the same.

 acceptOnLeave

return the acceptOnLeave flag. The default is false.
If true, leaving the box (via return, cursor etc.) accepts my
string into the valueHolder (if any).
(actually, the set of keys can be specified with #leaveKeys:)

 acceptOnLeave: aBoolean

set/clear the acceptOnLeave flag. The default is false.
If true, leaving the box (via return, cursor etc.) accepts my
string into the valueHolder (if any).
(actually, the set of keys can be specified with #leaveKeys:)

 acceptOnLostFocus

 acceptOnLostFocus: aBoolean

set/clear the acceptOnLostFocus flag. The default is false.
If true, a lost focus (via mouse-pointer motion etc.) accepts my
string into the valueHolder (if any).

 acceptOnPointerLeave: aBoolean

set/clear the acceptOnPointerLeave flag. The default is false.
If true, a pointer leave (via mouse-pointer motion etc.) accepts my
string into the valueHolder (if any).

 acceptOnReturn: aBoolean

set/clear the acceptOnReturn flag. The default is false.
If true, leaving the box via return accepts my
string into the valueHolder (if any).

 acceptOnTab: aBoolean

set/clear the acceptOnTab flag. The default is true.
If true, a pressed Tab key accepts and leaves the box.
If false, the Tab key is treated like any normal input character
(i.e. inserted into the contents).

 autoScroll: aBoolean

turn on/off automatic scrolling upon keyboard entry
to make the cursor visible.

 clickAction: aBlock

define an action to be evaluated when being clicked upon

 converter

return the converter (if any).

 converter: aConverter

set the converter. If non-nil,
the converter is applied to the text to convert from the string
representation to the actual object value and vice versa.
The default converter is nil, meaning no-conversion
(i.e. the edited object is the string itself.

 crAction: aBlock

define an action to be evaluated when the return key is pressed.

 doubleClickAction: aBlock

define an action to be evaluated when being double clicked upon

 enabled

return true, if the field is enabled (i.e. accepts keyboard input)

 enabled: aBoolean

enable/disable the field; show/hide the cursor and allow/disallow input

 entryCompletionBlock

the action to be evaluated when Tab (EntryCompletionCharacter) is pressed.
The block gets the current contents and the field itself as optional arguments
(i.e. it can be a 0, 1 or 2-arg block).

usage example(s):

read comment in entryCompletionBlockHolder: on why the following kludge is present

 entryCompletionBlock: aZeroOneOrTwoArgBlock

define an action to be evaluated when Tab (EntryCompletionCharacter) is pressed.
The block gets the current contents and the field itself as optional arguments
(i.e. it can be a 0, 1 or 2-arg block).

 entryCompletionBlockHolder: aZeroOneOrTwoArgBlock

a holder for an action to be evaluated when Tab (EntryCompletionCharacter) is pressed.
The block gets the current contents and the field itself as optional arguments
(i.e. it can be a 0, 1 or 2-arg block).

 entryCompletionCharacter

return the value of the instance variable 'entryCompletionCharacter' (automatically generated)

 immediateAccept: aBoolean

set/clear the immediateAccept flag. The default is false.
If true, every pressed key immediately accepts my
string into the valueHolder (if any).

 isAcceptOnLeave

return the acceptOnLeave flag. The default is false.
If true, leaving the box (via return, cursor etc.) accepts my
string into the valueHolder (if any).
(actually, the set of keys can be specified with #leaveKeys:)

 isAcceptOnLostFocus

return the acceptOnLostFocus flag. The default is false.
If true, a lost focus (via mouse-pointer motion etc.) accepts my
string into the valueHolder (if any).

 isAcceptOnReturn

return the acceptOnReturn flag. The default is false.
If true, leaving the box via return accepts my
string into the valueHolder (if any).

 isAcceptOnTab

return the acceptOnTab flag. The default is true.
If true, a pressed Tab key accepts and leaves the box.
If false, the Tab key is treated like any normal input character
(i.e. inserted into the contents).

 isImmediateAccept

return the immediateAccept flag. The default is false.
If true, every pressed key immediately accepts my
string into the valueHolder (if any).

 leaveAction: aBlock

define an action to be evaluated when field is left by a leave-key
(by default: return or cursor keys.
Actually, the set of keys can be specified with #leaveKeys:
On leave, the precedence of actions is:
1) explicit leaveAction per key
2) this general leaveAction
3) tab or return action

 leaveKey

only valid after the editField has been left via a leaveCharacter.
Allows for users of the EditField to advance the selection
(especially: DataSets to select next/prev if editor is left via CrsrUp/Down)

 leaveKeys

return (a copy of) the collection of keys which are interpreted as leaveKeys.
I.e. those that make the field inactive and pass the focus to the next field
(and accept, if acceptOnLeave is true)

 leaveKeys: aCollectionOfKeySymbols

define the set of keys which are interpreted as leaveKeys.
I.e. those that make the field inactive and accept (if acceptOnLeave is true).
The default is a set of #CursorUp, #CursorDown, #Next, #Prior and #Return.

 makeTabable

arrange for Tab to accept & leave the field
If the field is part of a group, the next field gets the
input focus

 onKey: aKey leaveWith: aBlock

arrange for aKey to leave the field and evaluate aBlock.
On leave, the precedence of actions is:
1) explicit leaveAction per key
2) general leaveAction
3) tab or return action
Can be used to arrange for cursorDown to pass focus to another widget,
or to override builtin ctrl- shortcuts.
The leave-action block will be called with 0,1 (the key) or 2 (self + key) arguments

 readOnly: aBoolean

make the text readonly or writable

 returnKeyIsFocusNext

arrange for the return key to act as a focus-next key

 tabAction: aBlock

define an action to be evaluated when the tabulator key is pressed.

 tabKey: aKeySymbol

arrange for aKeySymbol to accept & leave the field
If the field is part of a group, the next field gets the
input focus

 contents

return contents as a string
- redefined since EditFields hold only one line of text.
In your application, please use #editValue;
it uses a converter (if any) and is compatible to ST-80.

 contents: someText

set the contents from a string
- redefined to place the cursor to the end.
In your application, please use #editValue: -
it uses a converter (if any) and is compatible to ST-80.

 convertEditValueToString: aStringOrObject

convert a aStringOrObject to a printed representation.
If there is a converter, use it to convert
the object into a printed representation.
Use asString to convert the object,
and used directly.

 editValue

if the field edits a string, this is a name alias for #contents.
Otherwise, if there is a converter, return the edited string
converted to an appropriate object.

 editValue: anObject

set the contents. If there is a converter, use it to convert
the object into a printed representation.
Otherwise, convert anObject to a string using #asString
(this is equivalent to sending #contents:).

 editValue: anObject selected: isSelected

set the contents. If there is a converter, use it to convert
anObject into a printed representation.
Otherwise, use anObject asString
(i.e. this is equivalent to sending #initialText:selected:).

 initialText: aString

set the initialText and select it.
Better use #editValue: - it uses the type converter.

 initialText: aString selected: isSelected

set the initialText and select it if isSelected is true
Better use #editValue:selected: - it uses the type converter.

 list: someText

low level access to the underlying contents' list.
Redefined to force text to 1 line, and notify dependents
of any changed extent-wishes (for automatic box resizing).

 stringValue

alias for #contents - for compatibility with ST-80's InputField

 bePassword

make me a password entry field (i.e. show *'s for typed characters

 bePassword: aBoolean

if true, make me a password entry field (i.e. show *'s for typed characters

 emptyFieldReplacementText

the string to show in grey if nothing has been entered (and the field is passive)

 emptyFieldReplacementText: aString

the string to show in grey if nothing has been entered (and the field is passive)

 font: aFont

 maxChars

return the maximum number of characters that are allowed in
the field.
A limit of nil means: unlimited. This is the default.

 maxChars: aNumberOrNil

set the maximum number of characters that are allowed in
the field. Additional input will be ignored by the field.
A limit of nil or zero means: unlimited. This is the default.
If set, a lengthLimit must be defined before any contents is placed
into the field, because the contents is not cut when the max is
changed later. I.e. it should be set early after creation of the field.

This method has been renamed from #lengthLimit: for ST-80
compatibility.

 passwordCharacter

return the passwordCharacter;
If nonNil, that one is replacing typed input
(for secret input)

 passwordCharacter: aCharacter

set the passwordCharacter;
If nonNil, that one is replacing typed input
(for secret input)

 cursorShown: aBoolean

make cursor visible if currently invisible - but only if this
EditField is enabled.
Return the previous cursor-shown-state

 drawFromVisibleLine: startVisLineNr to: endVisLineNr with: fg and: bg

(comment from inherited method)
draw a visible line range in fg/bg

 cursorDown

catch cursor movement

 cursorLeft

(comment from inherited method)
move cursor to left

 cursorLine: line col: col

catch cursor movement

 cursorLine: line col: col makeVisible: aBoolean

catch cursor movement

 validateCursorCol: col inLine: line

check of col is a valid cursor position;
return a fixed value if not.

 dropFileObject: aDropObject

drop objects
Redefined to always drop the name only

 paste: someText

redefined to force text to 1 line

 buttonPress: button x: x y: y

enable myself on mouse click

usage example(s):

super buttonPress:button x:x y:y.

usage example(s):

super buttonPress:button x:x y:y

 buttonRelease: button x: x y: y

if the selection is empty (because of validateSelection,
clear it alltogether, so that the cursor becomes visible again

 canHandle: aKey

return true, if the receiver would like to handle aKey
(usually from another view, when the receiver is part of
a more complex dialog box).
We do return true here, since the editfield will handle
all keys.
OBSOLETE: don't use this anymore - its a leftover for the tableWidget

 doubleClickX: x y: y

 handleCompletionService

none here

 handleFocusKey: key

handle a focus key, to assign the focus to another field in my group

 keyPress: key x: x y: y

if keyHandler is defined, pass input; otherwise check for leave
keys

 keyboardZoom: largerBoolean

CTRL+/- zoom action

 pointerLeave: state

(comment from inherited method)
mouse pointer left

 resizeOrScroll

helper for keyPress.
Extracted for easier subclass redefinition.

 sizeChanged: how

scroll to origin, if all fits

 tripleClickX: x y: y

triple-click - select all

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:0.0@0.0 in:top.
    field width:1.0.                                'let its height as-is'.

    top open

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:0.0@0.0 in:top.
    field width:1.0.                                'let its height as-is'.

    top delegate:(KeyboardForwarder toView:field).
    field hasKeyboardFocus:true.
    top open

    |top field spacing|

    top := StandardSystemView new.
    top extent:200@100.

    spacing := View viewSpacing.
    field := EditField origin:(0.0 @ spacing) in:top.
    field width:1.0.                                        'let its height as-is'.
    field leftInset:spacing; rightInset:spacing.

    top open

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field width:1.0.

    field editValue:'hello world'.

    top open

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field width:1.0.
    field editValue:'hello world' selected:true.

    top open

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field width:1.0.

    field editValue:'hello world'.
    field selectFromCharacterPosition:1 to:5.

    top open

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field width:1.0.
    field editValue:'hello'.

    field maxChars:8.

    top open

    |top field|

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field innerWidth:(field font widthOf:'00000000').
    field editValue:'12345678'.

    field maxChars:8.
    field autoScroll:false.

    top open

    |top panel check field ena|

    top := StandardSystemView new.
    top extent:200@100.

    panel := VerticalPanelView origin:0.0@0.0 corner:1.0@1.0 in:top.
    panel borderWidth:0.
    panel horizontalLayout:#left.
    panel horizontalInset:View viewSpacing.

    check := CheckBox label:'enable' in:panel.
    check turnOn.
    check action:[:onOff | onOff ifTrue:[field enable] ifFalse:[field disable]].

    panel add:(View new height:30; borderWidth:0).

    field := EditField in:panel.
    field width:1.0.
    field editValue:'hello'.

    top open

    |top panel check field ena|

    top := StandardSystemView new.
    top extent:200@100.

    panel := VerticalPanelView origin:0.0@0.0 corner:1.0@1.0 in:top.
    panel borderWidth:0.
    panel horizontalLayout:#left.
    panel horizontalInset:View viewSpacing.

    ena := true asValue.

    check := CheckBox label:'enable' in:panel.
    check model:ena.

    panel add:(View new height:30; borderWidth:0).

    field := EditField in:panel.
    field enableChannel:ena.
    field width:1.0.
    field editValue:'hello'.

    top open

    |top field spacing|

    top := StandardSystemView new.
    top extent:200@100.

    spacing := View viewSpacing.

    field := EditField origin:0.0 @ spacing in:top.
    field width:1.0.
    field horizontalInset:spacing.

    field converter:(PrintConverter new initForNumber).
    field editValue:1234.
    field acceptAction:[:value | Transcript showCR:value].
    field crAction:[field accept. top destroy].
    top open.

    |top field spacing|

    top := StandardSystemView new.
    top extent:200@100.

    spacing := View viewSpacing.

    field := EditField origin:0.0 @ spacing in:top.
    field width:1.0.
    field horizontalInset:spacing.

    field converter:(PrintConverter new initForDate).
    field editValue:Date today.
    field acceptAction:[:value | Transcript showCR:value class name , ' ' , value printString].
    field crAction:[field accept. top destroy].
    top open.

    |top field spacing|

    top := StandardSystemView new.
    top extent:200@100.

    spacing := View viewSpacing.

    field := EditField origin:0.0 @ spacing in:top.
    field width:1.0.
    field horizontalInset:spacing.

    field converter:(PrintConverter new initForNumberOrNil).
    field immediateAccept:true.
    field editValue:1234.
    field acceptAction:[:value | Transcript showCR:value].
    field crAction:[field accept. top destroy].
    top open.

    |top field1 field2 field3 group|


    top := StandardSystemView new.
    top extent:200@100.

    field1 := EditField origin:(0.0 @ 0.0) in:top.
    field1 width:1.0.

    field2 := EditField origin:(0.0 @ 0.0) in:top.
    field2 width:0.5.
    field2 topInset:(field1 height); bottomInset:(field1 height negated).

    field3 := EditField origin:(0.5 @ 0.0) in:top.
    field3 width:0.5.
    field3 topInset:(field1 height); bottomInset:(field1 height negated).

    group := EnterFieldGroup new.
    group add:field1; add:field2; add:field3.

    top delegate:(KeyboardForwarder to:group).

    top open.

    |top field1 field2 field3 group|


    top := StandardSystemView new.
    top extent:200@100.

    field1 := EditField origin:(0.0 @ 0.0) in:top.
    field1 width:1.0.

    field2 := EditField origin:(0.0 @ 0.0) in:top.
    field2 width:0.5.
    field2 topInset:(field1 height); bottomInset:(field1 height negated).

    field3 := EditField origin:(0.5 @ 0.0) in:top.
    field3 width:0.5.
    field3 topInset:(field1 height); bottomInset:(field1 height negated).

    group := EnterFieldGroup new.
    group add:field1; add:field2; add:field3.
    group leaveAction:[top destroy].

    top delegate:(KeyboardForwarder to:group).

    top open.

    |top field model|

    model := 'hello world' asValue.

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field width:1.0.
    field model:model.
    field acceptOnReturn:true.

    top open.
    model inspect.

    |top field model|

    model := 'hello world' asValue.

    top := StandardSystemView new.
    top extent:200@100.

    field := EditField origin:(0.0 @ 0.0) in:top.
    field width:1.0.
    field model:model.
    field acceptOnLostFocus:true.

    top open.
    InspectorView openOn:model monitor:'value'.

    |top1 top2 field1 field2 model|

    model := 'hello world' asValue.

    top1 := StandardSystemView new.
    top1 extent:200@100.
    field1 := EditField origin:(0.0 @ 0.0) in:top1.
    field1 width:1.0.
    field1 model:model.
    field1 acceptOnReturn:true.
    top1 open.

    top2 := StandardSystemView new.
    top2 extent:200@100.
    field2 := EditField origin:(0.0 @ 0.0) in:top2.
    field2 width:1.0.
    field2 model:model.
    field2 acceptOnReturn:true.
    top2 open.

    |top1 top2 field1 field2 model|

    model := 'hello world' asValue.

    top1 := StandardSystemView new.
    top1 extent:200@100.
    field1 := EditField origin:(0.0 @ 0.0) in:top1.
    field1 width:1.0.
    field1 model:model; acceptOnReturn:false.
    top1 open.

    top2 := StandardSystemView new.
    top2 extent:200@100.
    field2 := EditField origin:(0.0 @ 0.0) in:top2.
    field2 width:1.0.
    field2 model:model; acceptOnReturn:false.
    top2 open.

    |top1 top2 field1 field2 model|

    model := 'hello world' asValue.

    top1 := StandardSystemView new.
    top1 extent:200@100.
    field1 := EditField origin:(0.0 @ 0.0) in:top1.
    field1 width:1.0.
    field1 model:model; immediateAccept:true.
    top1 open.

    top2 := StandardSystemView new.
    top2 extent:200@100.
    field2 := EditField origin:(0.0 @ 0.0) in:top2.
    field2 width:1.0.
    field2 model:model; immediateAccept:true.
    top2 open.

    |top1 top2 field1 box model|

    model := false asValue.

    top1 := StandardSystemView new.
    top1 extent:200@100.
    field1 := EditField origin:(0.0 @ 0.0) in:top1.
    field1 width:1.0.
    field1 converter:(PrintConverter new initForYesNo).
    field1 model:model.
    top1 open.

    top2 := StandardSystemView new.
    top2 extent:200@100.
    box := CheckBox on:model.
    box label:'on/off'.
    top2 add:box.
    top2 open.

    model inspect.

    |top panel group field1 field2 field3 box
     v1 v2 v3 spacing|

    v1 := true asValue.
    v2 := 'some string' asValue.
    v3 := 1.2 asValue.

    top := StandardSystemView new.
    top extent:200@100.

    panel := VerticalPanelView origin:0.0 @ 0.0 corner:1.0 @ 1.0 in:top.

    spacing := View viewSpacing.

    field1 := EditField new.
    field1 width:1.0.
    field1 horizontalInset:spacing.
    field1 converter:(PrintConverter new initForYesNo).
    field1 model:v1.
    panel add:field1.

    field2 := EditField new.
    field2 width:1.0.
    field2 horizontalInset:spacing.
    field2 model:v2.
    panel add:field2.

    field3 := EditField new.
    field3 width:1.0.
    field3 horizontalInset:spacing.
    field3 converter:(PrintConverter new initForNumber).
    field3 model:v3.
    panel add:field3.

    group := EnterFieldGroup new.
    group add:field1; add:field2; add:field3.

    top openModal.

    Transcript showCR:v1 value.
    Transcript showCR:v2 value.
    Transcript showCR:v3 value.

    |application top field1 field2 value1 value2|

    application := Plug new.
    application respondTo:#value1Changed
                     with:[value2 value:(value1 value isNil ifTrue:[nil]
                                                            ifFalse:[value1 value squared])].

    value1 := 1 asValue.
    value2 := 1 asValue.

    top := Dialog new.
    top extent:200@200.

    (top addTextLabel:'some number:') layout:#left.
    top addVerticalSpace.

    (top addInputFieldOn:value1 tabable:false)
        converter:(PrintConverter new initForNumberOrNil);
        immediateAccept:true.
    top addVerticalSpace.

    (top addTextLabel:'squared:') layout:#left.
    top addVerticalSpace.
    (top addInputFieldOn:value2 tabable:false)
        converter:(PrintConverter new initForNumberOrNil).

    value1 onChangeSend:#value1Changed to:application.

    top openModeless.

    |application top field1 field2 value1 value2|

    application := Plug new.
    application respondTo:#value1Changed
                     with:[value2 retractInterestsFor:application.
                           value2 value:(value1 value isNil ifTrue:[nil]
                                                            ifFalse:[value1 value squared]).
                           value2 onChangeSend:#value2Changed to:application.
                          ].
    application respondTo:#value2Changed
                     with:[value1 retractInterestsFor:application.
                           value1 value:(value2 value isNil ifTrue:[nil]
                                                            ifFalse:[value2 value sqrt]).
                           value1 onChangeSend:#value1Changed to:application.
                          ].

    value1 := 1 asValue.
    value2 := 1 asValue.

    top := Dialog new.
    top extent:200@200.

    (top addTextLabel:'some number:') layout:#left.
    top addVerticalSpace.

    (top addInputFieldOn:value1 tabable:false)
        converter:(PrintConverter new initForNumberOrNil);
        immediateAccept:true.
    top addVerticalSpace.

    (top addTextLabel:'squared:') layout:#left.
    top addVerticalSpace.
    (top addInputFieldOn:value2 tabable:false)
        converter:(PrintConverter new initForNumberOrNil);
        immediateAccept:true.

    value1 onChangeSend:#value1Changed to:application.
    value2 onChangeSend:#value2Changed to:application.

    top openModeless.