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IDProjectCategoryView StatusLast Update
0037815LazarusLCLpublic2020-09-27 20:47
ReporterChris Rorden Assigned To 
Status newResolutionopen 
PlatformRyzen 3900xOSUbuntu 20.04 
Product Version2.1 (SVN) 
Summary0037815: GTK3: TTrackbar Frozen if Form has Panel
DescriptionWith GTK3, one can not move the position of a trackbar if the form has a Panel.
Steps To ReproducePlace TTrackBar and TPanel on Form, run program. Attempt to move trackbar.
TagsNo tags attached.
Fixed in Revision
WidgetsetGTK 3
Attached Files


Chris Rorden

2020-09-25 22:26

reporter (108,961 bytes)

Anton Kavalenka

2020-09-26 07:51

reporter   ~0125865

Can not reproduce. Trackbar is moving either by mouse or keyboard [PgUp] [PgDn]
Maybe try remove the lazarus/lcl/units/*

Juha Manninen

2020-09-26 11:24

developer   ~0125866

Last edited: 2020-09-26 11:25

View 2 revisions

I can reproduce in my Manjaro + KDE system.
The numeric part works and gets updated but the graphical slider does not. Strange, how can a native GTK3 widget work only partially?
Indeed if I remove the Panel, the graphical slider works.
One more issue: if I add a TrackBar onto the Panel as in Anton's screenshot, the application refuses to close. It must be killed.

This must be related to a desktop system or to library versions. My Manjaro has KDE and recent versions of libs.
Ubuntu 20.04 has either Gnome or Unity. Which is it?
Anton, your system appears to be more GTK3 friendly. What is it?
GTK3_trackbar_JuMa.png (9,609 bytes)   
GTK3_trackbar_JuMa.png (9,609 bytes)   

Anton Kavalenka

2020-09-26 12:06

reporter   ~0125869

My desktop and notebook both Debian GNU/Linux 10.4 stable with GNOME 3.28

Anton Kavalenka

2020-09-26 13:21

reporter   ~0125870

This problem may be related to themes.
AFAIK there is special packages that make GTK and QT appear similar with current chosen theme.
These packages has to be installed separately.

Juha Manninen

2020-09-27 18:40

developer   ~0125904

I doubt it is only about themes.
Remember, a Panel on the form affects the behavior even when it is not the Parent of the TrackBar.

Anton Kavalenka

2020-09-27 18:49

reporter   ~0125905

Last edited: 2020-09-27 20:47

View 3 revisions

ufff, got to install Plasma desktop ...

Can confirm. Thumb not moves.

What I found:
* Not just panel placed to a form prevents TrackBar update but aligned panel (Align<>alNone).
* Manually resizing (slightly drag the corner of Form) restores proper behavior of Trackbar. This make any pending size updates finished.

The resume - Alignment leaves WS sizing state unfinished under non-GTK window manager.

Issue History

Date Modified Username Field Change
2020-09-25 22:26 Chris Rorden New Issue
2020-09-25 22:26 Chris Rorden File Added:
2020-09-26 07:51 Anton Kavalenka Note Added: 0125865
2020-09-26 07:51 Anton Kavalenka File Added: Здымак экрана, 2020-09-26 08-48-41.png
2020-09-26 11:24 Juha Manninen Note Added: 0125866
2020-09-26 11:24 Juha Manninen File Added: GTK3_trackbar_JuMa.png
2020-09-26 11:25 Juha Manninen Note Edited: 0125866 View Revisions
2020-09-26 12:06 Anton Kavalenka Note Added: 0125869
2020-09-26 13:21 Anton Kavalenka Note Added: 0125870
2020-09-27 18:40 Juha Manninen Note Added: 0125904
2020-09-27 18:49 Anton Kavalenka Note Added: 0125905
2020-09-27 19:50 Anton Kavalenka Note Edited: 0125905 View Revisions
2020-09-27 20:47 Anton Kavalenka Note Edited: 0125905 View Revisions