It is not hard to see such tool windows that stay always above the
main form, but are modeless and are not above other applications'
windows. Is this achievable with pure BCL? The only thing I know is
using TopMost property. But this makes the form stays above all other
application's windows. Should I use Win32 API for this?

What I want is another form that the main form, which is;
1) modeless
2) Stays always above the main form
3) But not always on the windows of other applications
4) and not an MDI child form, nor the main form is a MDI parent form.

Thanks for any hints.