ActiveX form in C#

Question

I have a VB6 ActiveX DLL in which I have methods that allow me to call a VB6 form within the VB6 DLL application. I am using COM interop in C# to link to this DLL, and am trying to open VB forms from within my C# windows app. The problem is that it only allows me to run VB forms Modally. I want to be able to open my forms in Modeless mode, i.e frmMyForm.Show if I attempt this i get the following error. Error 406: Non-modal forms cannot be displayed in this host application from an ActiveX DLL, ActiveX Control, or Property Page So am I stuck with only being able to open Forms in Modal mode from within C# or is there another way. OR if anyone knows how I can open a VB6 form in Modeless mode (not Modal), from with C#, Please help me. Thanks.

shazadali · Answer

It was a case of converting my ActiveX DLL written in VB6 to make it an ActiveX exe instead. I don't know the technical reason why I needed to this. Everything on the C# side is the same. Modeless forms can then be invoked. If anyone still has a way of doing this without converting a project into an ActiveX exe then please let me know as it would still be useful when it may not be possible to convert a dll.

Mahesh Chand · Answer

Writing a FAQ on this would be a good help for other developers. Perhaps ;)

shazadali · Answer

I managed to solve my problem by using an out of process activeX exe.

jcity444 · Answer

I suspect that modal forms work because they run on their own message pump where as modeless forms depend upon the hosts message pump. Unfortunately I suspect the message loop of a managed .NET application looks a bit different than that of a compiled VB6 application so you may not be able to do this. -Mike