UPDATE 2019-12-16: Official patch available.
Unfortunately, the long-awaited Delphi 10.3.3 release also brought a few new issues. One of them is that TActionManager is broken in a way, that prevents projects, using it, from compiling.
Because of some scope issue, the IDE keeps adding a unit named „IDETheme.ActnCtrls.pas“ to any form unit, that contains a TActionManager, once you save that form unit. „IDETheme.ActnCtrls“ is invalid, does not exist, thus the whole project will not compile anymore.
Fortunately, until EMBT releases a hotfix, there is a relatively easy workaround:
- Add „VCL.ActnCtrls“ to any affected form unit
- Create and add a completely empty unit to your project and name that unit „IDETheme.ActnCtrls.pas“