Fading in/out of 2 forms parallel in Delphi with Firemonkey
Solution 1:
An FMX Form does not natively support what you are asking for.
However, when run on Windows, a Form does have a Win32 HWND assigned to it (which you can obtain using FMX.Platform.Win.FormToHWND()). As such, you can use the Win32 API SetLayeredWindowAttributes() function to manually assign a translucency value to the window.