How to not have a MainForm in Delphi?

Question

i've been trying to get some modeless forms in my application to appear on the taskbar - taking advantage of the new useful taskbar in Windows 7.

There's are many issues with the VCL that need to be undone before a form can exist on the taskbar.

But the final issue is that minimizing the form that the VCL has designated the main form causes all windows in the application to vanish.

Ten years ago, Peter Below (TeamB) documented these problems, and attempts to work around them. But there are some issues that cannot be solved. The issues run so deep within the VCL itself, that it's effectively impossible to make Delphi applications behave properly.

It all stems from the fact that the button you see on the toolbar does not represent the application's window; it represents the TApplications window, which is hidden and never seen. And then there is the application's MainForm, which is then imbued with special abilities where if it is minimized then it instructs the application to hide itself.

It seems to me that if i can do

Application.MainForm := nil;

then all these bugs would go away. The application can have its hidden window, and in the meantime i'll override every other form in the application, including my main form, with:

procedure TForm2.CreateParams(var params: TCreateParams ); 
begin 
   inherited CreateParams(params); 
   params.ExStyle := params.ExStyle or WS_EX_APPWINDOW; 
end; 

But in Delphi the Application.MainForm property is read-only.

How can i not have a MainForm in Delphi?

See also

• (stackoverflow) Delphi: What is Application.Handle?
• (newsgroup) Hiding Main Window but not child

Answer 1

You can't, especially in Delphi 5.

Your quote concerning the TApplication window being the one seen on the task bar hasn't been true for several Delphi versions now (I believe D2007 changed it).

Because you're using Delphi 5, you're using an outdated copy of Delphi; current versions have almost none of the things you're writing about any longer. I'd suggest you upgrade to a later version of Delphi (D5 is extremely old); Delphi 2007 if you need to avoid Unicode, Delphi XE if you can use (or don't mind having) Unicode support in the VCL and RTL.

The things you're describing are not bugs, BTW. They were intentional design decisions made at the time Delphi 1 was being designed, and through Delphi 7 worked fine with the versions of Windows that were available. Changes in later versions of Windows (XP/Vista/Win7 and the equivalent Server versions) made changes in that architecture necessary, and they were made as Delphi progressed along with Windows. Because you've chosen not to progress with your version of Delphi to keep it more recent doesn't make the things you write about magically become bugs. :-)

Answer 2

You can put your modeless forms in a dll, then they act pretty much on their own. (If you do not use the Application instance of the dll while creating them (Application.CreateForm) then Application.Mainform is nil in the dll).

Of course this might not be feasible depending on what the forms might need to do.

Answer 3

You cannot run a GUI project without a MainForm assigned. The main message loop will exit immediately without one. However, that does not mean that the MainForm has to run your UI. You can use a blank hidden TForm as the assigned MainForm, and then have it instantiate your real MainForm as a secondary TForm.