Delphi 10.4 - Autohide Taskbar + CustomTitleBar - Taskbar does not show up, when window is maximized

[jaenicke 13]

Hello,

 

in Delphi 10.4 and Delphi 11 there is a problem with the taskbar. If you use the CustomTitleBar and maximize the window, the taskbar does not show up if it is set as automatically hidden. This applies to own programs as well as to the Delphi IDE.

 

Since this has been fixed with Delphi 12, I no longer need to create a bug entry and there was already one for the Delphi IDE, in which I wrote that it works with Delphi 12.

 

My problem now is that I have no idea what change in the VCL did the fix. I already searched, but have not found anything suitable. I have transferred the Vcl.TitleBarCtrls unit completely as a test, but that was not successful. Does anyone have any idea where the cause of the problem could lie, so that I can transfer the fix to Delphi 10.4?

 

Many thanks to all readers!

Sebastian

[jaenicke 13]

I found it:

One has to implement WMNCCalcSize in the form and, if the window is maximized, decrement NCCalcSizeParams.rgrc[0].Bottom or NCCalcSizeParams.rgrc[0].Right by one, so the taskbar can be activated there.