[Lazarus] What are "widgets" in lazarus?

Graeme Geldenhuys graemeg.lists at gmail.com
Thu Jan 13 08:07:00 CET 2011


Op 2011-01-09 20:24, Hans-Peter Diettrich het geskryf:
> Where do you see problems?
....

> The determination of a closer target (e.g. control) is up to the
> application or library, that manages the layout of a window. Every
> application or library can freely define their own "handles" for every


Try and implement your own GUI toolkit, and we talk again.

Just some (not all) of the problems Qt had to overcome are as follows:

 * XDND protocol requires mouse enter, exit and window properties to
   correctly get a source or target of a drag action. X11 Window
   handles are required for this.

 * Windows OLE drag-n-drop protocol requires window handles for each
   window or widget that can do DND.

 * Window clipping must now be handled by Qt itself.

 * Window clipping between non-handle windows and handle-windows.
   eg: The form has a handle, but all normal widgets on that form
   have no handles. Now through in a OpenGL widget which must have
   a window handle. Now you have widgets on the form that has handles,
   and some that don't. Now apply all the previous items listed to the
   mix.

Qt managed to do all this and more, without breaking existing
applications and code! That is pretty incredible.

So from a Qt end-users point of view, it is business as normal. But
internally, Qt has changed dramatically from a design where you had a
window handle per widget, to a single window handle per Form. Hats off
to them for pulling it off without a hitch. And they didn't even bump up
the major version for this change, they simply went from 4.3 to 4.4
[those cocky bastards :-)]


Regards,
  - Graeme -

-- 
fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal
http://fpgui.sourceforge.net/





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