TTabControl rendered incorrectly?

[Cascade]

When I add a TTabControl to a form, the control seems to be rendered incorrectly.  The tab buttons are shifted to the left, and there is an overlapping box underneath.  It looks quite similar to a PageControl, but I'm not sure whether there is a connection there.

I've attached a screenshot which explains the issue better than words.  It shows a TabControl with two tabs at the top, and then a PageControl below for comparison.

How might I get TTabControl to render correctly?

[Hansaplast]

I never use TabControl but can confirm this to be indeed a bug.
Just tried it on Tahoe with Lazarus from trunk and there we see this as well.


FYI for the devs: Lazarus 4.99 (rev main_4_99-2073-g15a44331c3) FPC 3.3.1 x86_64-darwin-cocoa

You should probably open a bug report (here).

[Nicole]

Not sure, if my observations can help.
I use TPageControl much and there Tabsheets. As I thought over to switch from Windows to Linux I spent some time on their behaviour.

Those are done by Windows in a way, that they are arranged by themselves. When there are too many for one line, the line with the Tabsheets is wrapped into the next line.

Not so Linux: There you can shift them from left to right and do not see them all.

You will say: What may this have to do with my thing? I wonder, if the strange box you see may be related with the different way to handle it by operating systems.

If you can, try this: Try the code on Linux, if you run Windows and vice versa. And find out, if the problem persists or modifies or even is gone.

[Cascade]

  Thanks for the replies Nicole and Hansaplast.

I've opened an Issue here:
https://gitlab.com/freepascal.org/lazarus/lazarus/-/issues/41854

[Hansaplast]

Added a thumbs up in Bug Tracker 😉

[wp]

Just to confirm: The same issue can be seen in macOS Monterey 12 with Laz/main + fpc 3.2.2