Recompiled IDE with LCLRealFormBounds On -> problem

[AlexTP]

Wiki tells about this define
https://wiki.lazarus.freepascal.org/Autosize_/_Layout

1. I run IDE on Win32, it shows its main window normally.
2. I opened "Configure Build Lazarus" dialog and added there define LCLRealFormBounds, checked "Clean all" and recompiled the IDE
3. After IDE restart, its window is shrunk by Y. I cannot resize it. Even maximize/restore don't help.

2 screenshots: normal window, shrunk window.
Win10 x64.
FPC 3.2.3.
Lazarus: Git 'main'.

[AlexTP]

This option makes it bad:
Window > Automatically adjust IDE main window height