[lazarus] some questions about design

[Marc Weustink]

+ From: Stefan Hille [mailto:stoppok at osibisa.ms.sub.org]
+
+ Hi,
+
+ hope you've all recovered now from your millenium parties;-)

:-)

+ Ok, here some things I've noticed during the last days of development:
+
+ - There's a problem with all classes derived from TGraphicControl.
+   (currently these are TPaintBox and TBevel).
+   The problem is, that there are a lot of places where these
+   are casted to TWinControl, although TGraphicControl is
+   derived from TControl.

Hmm... odd, I first thought this was an historical point, but since the
introduction (1.15) is had been derived from TControl. I think these casts
should be altered.

+   any suggestions how to solve this?
+
+ - TCheckBox is quite OK now, but if you assign OnClick and
+   try to find out if the object is checked/unchecked you'll get
+   the wrong state. Seems as if GTK is calling the handler before
+   it actually changes the state.

It looks like the state is changed on a keyup instead of a key down
The order of events is currently
LM_[KEY|BUTTON]DOWN : triggered by gtk event
LM_[CHAR|CLICK] : generated after down

LM_[KEY|BUTTON]UP : triggered by gtk event.

Hmmm... I just did some experiments in Delphi and it seems that I generate
the click event to early. It should be part of XXXUP and not XXXDOWN. I'll
fix that tonight.

+ - I'm not sure about it but it seems to me as if some controls (e.g.
+   TCustomForm) don't recognize if their visual representation changes.
+   For example if you resize a form the width/height properties won't get
+   updated.
+   Could anybody please check this.

Noticed that before. Could be caused by the recent change of messages. For
me it had a low priority, but if somebody else can look after it...

+ - To keep the properties of TTrackBar / TCheckBox up to date
+   I introduced some messages (LM_GETCHECKBOX...) which will
+   sync the state of the lazarus object with that one of the
+   GTK library. I think that we'll need more of these messages
+   in the future and I'd like to create one special
+   message for this. In the gtk interface we could then make a
+   new procedure which makes a "case fCompStyle of". Thus we
+   could avoid a lot of different messages.
+   Any comments?

You mean a message like LM_UPDATEVALUES ??? Sounds ok for me.

Marc