Nice theme! I like it, but you've made a little mistake: The icons for the main window and the message window are called "MainWindow.ico" and "MessageWindow.ico", not "PopMan.ico" and "Message.ico".
Maybe you can also change the message window icon: The border is too light for the blue background of the window title.
Regarding the toolbar Bitmap: PopMan uses the color of the leftmost bottom pixel as the background color. All pixels in the bitmap that have the same color are replaced with the system background color (which may be different from system to system). But until now this only works for bitmaps with up to 256 colors (8 Bit). Since your toolbar bitmap is a 24 bit color bitmap, the background color is not properly adjusted to the system color. But you can save the toolbar bitmap with 8 bit color depth, as Paul did, because there are only 253 colors used.
I think, I will make PopMan accept 24 bit color bitmaps too with Beta 11 (your upcoming Qute theme seems to use lots of colors!). Maybe I will also add the possibility to use a "toolbarDisabled.bmp" bitmap, that contains all the icons used for disabled toolbar buttons. The windows standard way of graying out the icons looks a bit ugly, ecspecially for high color icons...