In RAD Studio XE3 the option (located in Tools > Options > Environment Options > VCL Designer > Embedded Designer ) to disable the Embedded Designer was hide. Personally I still using the old floating designer when I work in VCL projects.
So if you want disable the Embedded Designer just go to the the windows registry key HKEY_CURRENT_USER\Software\Embarcadero\BDS\10.0\Form Design and set the Embedded Designer value to False
Note : Remember which FireMonkey only supports the embedded form designer.
