Re: [platform-ui-dev] TextEditorActions and selection/position-dependen

[Kai-Uwe Maetzel <maetzel@xxxxxxx>]

Robert,

The behavior you are seeing is inherited from the SWT StyledText widget.
When adding a SelectionListener to a StyledText instance you experience
the same behavior. The addition provided by the TextViewer is the
adaptation to the selection protocol of the class Viewer and the fact
that selection change events are also sent out on programmatic changes of
the selection. The AbstractTextEditor implements an approximation to a
"cursor position listener" by registering itself as KeyListener
and MouseListener on the StyledText widget.

Kai

At 05:06 PM 4/21/2003 -0400, you wrote:
> I've got a TextEditorAction that I
> want to be both selection-
> and position-activated, i.e. so that it's enabled at some
> textual positions but not others.
>
> So, I've marked it as selection-dependent; i.e., I called
> AbstractTextEditor.markAsSelectionDependentAction(myAction).
>
> I've found that changing the cursor position doesn't always
> result in calling an action's IUpdate.update(), so my action
> doesn't always get the chance to enable/disable itself.
>
> Specifically, if the selection is empty, cursor motion via the
> arrow keys or mouse pointer does NOT call update().
>
> If the selection is NON-empty, cursor motion via the arrow keys
> or mouse DOES call update() (presumably since the selection goes
> from non-empty to empty).
>
> One could argue that this is all a red herring since I can work
> around the problem by not attempting to enable/disable my action,
> but rather make it a no-op if the position is not one it should
> handle.
>
> On the other hand, I think that an empty selection is still a
> selection (zero length but at a specific document offset), so
> moving the cursor from one spot to another changes the selection,
> but clearly AbstractTextEditor disagrees with me. :-)
>
> Thoughts?
>
>
> --------------------------------
> Dr. Robert M.
> Fuhrer                        
> rfuhrer@xxxxxxxxxxxxxx
> Programming
> Technologies          
> IBM T. J. Watson Research Center
>
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