Mixing Windows API and GTK+

[Douglas Vechinski <douglas vechinski dynetics com>]

I have a gtk+ application that I developed under Linux.  I "ported" to 
Windows using the MSYS/MINGW environments along with the native window 
compilation of GTK+.  Now someone is interested in have me create a DLL 
out of this code so that it can be used as part of another Windows 
applications.  While one question pertains to how do I create a DLL 
using the MSYS/MINGW environment but is not related to this list.  My 
question for this list is, can there be a problem with mixing a Windows 
code that uses then WINAPI to create windows and such and call a 
function that would essentially create my GTK+ window and its associated 
widgets and mouse events and such or should everything work ok.