I'm developing a typical 3D application, where a modeless dialog box allows the user to set the rendering width and height, and when the user clicks Render, a modal render progress dialog box is shown and rendering starts.

I'm opening the Progress dialog box with a ShowModal call... but I haven't found the threads combination to be able to show the progress dlg, and start rendering right away.
And there is also a View Image modeless panel which shows the image that is being rendered (the image is updated every time a 32x32 pixels bucket is rendered.) This View Image panel needs to be accesible and ready for mouse input to display information about the image itself (colors, alpha, elements, etc.)
Does anybody knows a way to handle this correctly?
thank you,
Diego