#2196 Scrollbars do not work properly

[Vegeta]

I installed SciTE from the Arch Repository and the version does not work properly under Xfce. The scrollbars (horizontal and vertical) do not react after starting the editor. Only when you open a dialog or the menu they suddenly go. I made a screencast to show the problem: https://www.dropbox.com/s/wefn48t7lczqbfb/screencast.gif?dl=0

Arch Linux
Desktop: Xfce (gtk2 2.24.32-2 and gtk3 1:3.24.22-1)
SciTE Version 4.4.3 compiled for GTK 3.24.21

[Neil Hodgson]

May be https://gitlab.gnome.org/GNOME/gtk/-/issues/615 .

Does it start working if you resize the window?

[Vegeta]

Yes, as soon as I change the size of the window the scrollbars working immediately.

[Neil Hodgson]

After reading the GNOME issue, it appears that some applications worked around this problem by deferring handling to an idle or timer callback. The attached patch does this for Scintilla and appears to fix the problem on Ubuntu 20.04 when loading a file from the command line.

[Vegeta]

I ran the patch and compiled SciTE 4.4.4 with GTK3=1, now it works perfectly. Thanks a lot!

[Neil Hodgson]

Unfortunately, the patch appears to cause more problems.

From the mailing list:

all looks fine - but as soon as I move the mouse over the SciTE window
the scrollbar changes size (not a major problem, but...) - then
clicking on the window, pressing Page Down once - The scrollbar doesn't
move - until I move the mouse over the scrollbar. It's like the
scrollbar doesn't get updated properly.

I have reproduced this problem and haven't been able to find a good workaround. Without the patch, the scrollbar can be made to work by resizing the window (or switching to another application with Alt+Tab then back to SciTE with a second Alt+Tab). With the patch, there isn't an easy way to make it work.

[Vegeta]

I can reproduce the behaviour, the scrollbar sometimes doesn't react at all with Page Up / Down or with a delay. I haven't seen this with any other program so far, but it's a smaller problem for me than if the scrollbar fails completely.

[Andreas Rönnquist]

I'm the one who reported the "From the mailing list:" above - For me it's much better if I only have to resize the window before it behaves properly, rather than the scrollbar might be in the wrong position at any time no matter what I do.

[Neil Hodgson]

Trying to work out why changing to another application then back starts working and thought it could be a focus issue. However opening a find strip (Ctrl+F) moves focus to the strip but doesn't help with scrolling the main pane.

Turning on the status bar (Alt+V S) makes the scrollbar move with page down|up but not respond to dragging on the scrolbar. Switching the status bar off returns the scrollbar to non-moving. Showing then hiding the output pane (F8 F8) makes the scroll bar work.

Turning wrap off (but not on), which shows the horizontal scrollbar, stops the vertical scrollbar working which aligns with the abovementioned GNOME issue.

Moving the initial showing of the vertical scroll bar to idle time and avoiding other show/hide of either scrollbar, as implemented in the attached patch, does help. However, the problem recurs later such as after performing a find (Ctrl+F). Moving the horizontal scrollbar can restore movement to the vertical scrollbar.

[Neil Hodgson]

There's a patch on [#2322] that seems to fix this problem.

[Andreas Rönnquist]

After some minor testing I can say that it seems to fix it for me too. Thank you very much Neil!

[Neil Hodgson]

A potential fix has been committed as [0b5fb5].