[news.eclipse.platform.swt] Re: [SWT] curious focus behaviour

["Randy Hudson" <none@xxxxxxxxxx>]

"Grant Gayed" <grant_gayed@xxxxxxxxxx> wrote in message
news:baim6k$m23$1@xxxxxxxxxxxxxxxx
> Andre,
>
> #setFocus will set the focus in a platform-appropriate way, so this can
> reveal differences between win32 and motif for instance (though it should
> never cause a StackOverflow, unless it's a result of you having a focus-in
> listener who reassigns focus elsewhere but the platform puts it in the

Actually, that would still be an SWT bug.  If a control already has focus
and it is given focus again, it should not fire focus gained.  Or maybe it
should, but it should do the same thing on all platforms.

> same place, thereby re-notifying your focus-in listener again, etc.).
>
> #forceFocus should really force focus to the specified widget, so there
> should not be a platform difference if you use this.  If you have a simple
> test case that shows this behaving inconsistently then please log a bug
> report with Platform - SWT.
>
> Grant
>
> Andre wrote:
>
> > hello..
>
> > I recently stumbled over some curious focus behaviour:
> > if I call a widget's forceFocus() or setFocus() method, it works fine on
> > SWT.WIN32 (XP) but doesn't on SWT.motif (Linux and Solaris) and
SWT.photon
> > (QNX). On SWT.gtk (Linux) it even may cause a stack overflow.
>
> > My questions are: is that a bug or is that _really_ a platform specific
> > behaviour? Is there I way to realy force a widget to get the focus - on
> > every platform? I thought that if it's part of the API it should work
> > everywhere..
>
> > Thanks in advance
> > Andre
>
> > PS: a short sample code that demonstrates this problem:
>
> > public class CuriousFocus
> > {
> > public static void main(String[] args)
> > {
> > Display display = new Display();
> > Shell shell = new Shell(display);
>
> > final Canvas widget1 = new Canvas(shell, SWT.BORDER);
> >
>
widget1.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
> > widget1.addFocusListener( new FocusListener()
> > {
> > public void focusGained(FocusEvent e)
> > {
> > System.out.println("widget1::focusGained()");
> >
> widget1.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_RED));
> > widget1.redraw();
> > }
>
> > public void focusLost(FocusEvent e)
> > {
> > System.out.println("widget1::focusLost()");
> >
>
widget1.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
> > widget1.redraw();
> > }
> > });
>
> > final Canvas widget2 = new Canvas(shell, SWT.BORDER);
> >
>
widget2.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
> > widget2.addFocusListener( new FocusListener()
> > {
> > public void focusGained(FocusEvent e)
> > {
> > System.out.println("widget2::focusGained() \n");
> >
> widget2.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_RED));
> > widget2.redraw();
> > }
>
> > public void focusLost(FocusEvent e)
> > {
> > System.out.println("widget2::focusLost()");
> >
>
widget2.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
> > widget2.redraw();
>
> > // grab keyboard focus forever here
> > widget2.forceFocus();
> > //widget2.setFocus();
> > }
> > });
>
>
> > shell.setLayout( new FillLayout());
> > shell.open();
>
> > //shell.setSize(200, 100);
> > shell.pack();
>
> > while (!shell.isDisposed())
> > {
> > if (!display.readAndDispatch())
> > {
> > display.sleep();
> > }
> > }
> > display.dispose();
> > }
> > }
>
>
>
>