Even though it is not officially supported by Embarcadero there are many examples showing that you can include a FMX form in a VCL application e.g. MonkeyMixer and this SO question.
However, when I create a test application with only one empty VCL form and one empty FMX form, I get two problems:
There are two application icons in the task bar (apparently one for
each instance of TApplication i.e. VCL and FMX)
It crashes when I close the application (when it calls TStyleManager.UnInitialize in FMX.Forms.FinalizeForms).
How can I make this work?
I need this combination as we want our application to be native on Windows, Mac OS and iOS. Therefore on Windows it is a VCL application and the other OS’s are FMX using the TMS native components. We have some large custom graphical components that are made for FMX, and they must also work on Windows.
I see only two alternative solutions, and I like none of them:
Use FMX on Windows too. I don’t like the idea of styled components instead of native. Experienced users can easily tell the difference.
Maintain to sets of our custom components: VCL and FMX editions. That will require some work, and also the graphical features of FMX are much better than VCL.