[gtk-win32] Updating a progress bar from a worker thread

["John Emmas" <johne53 tiscali co uk>]

Recently, I downloaded the gtk-win32 tools that I found here:-

http://www.gtk.org/download-windows.html

including the recommended dependencies, such as 'win_iconv', 'libpng' and
'gettext' etc.  Having got through the stage of building a simple "Hello
World" app, I thought it was time to try my hand at something a bit more
adventurous (not *too* adventurous - but maybe another stage forward).

I built an app whose main window is derived from Gtk::Window.  It holds a
Vbox which contains a progress bar at the top, then a horizontal separator,
and finally, a button at the bottom.  The basic idea is that when the user
presses the button, it starts a worker thread which periodically signals the
main GUI thread to update the progress bar.  I've used pthread_win32 for the
threading and libsigc for the signals.

When I click on the button, the progress bar does indeed update - but with a
strange problem....  the updates only occur (visually) if:-

1)  I keep my mouse cursor positioned over the GTK app, and
2)  If I physically move the mouse.

If I hold the mouse stationary (or move it outside of the GTK main window)
the visual updates just don't happen (although I can tell that the update
function must be getting called).

Since yesterday I've tried several different strategies for implementing the
updates.  For example, I started off by sending a signal from the worker
thread to the GUI thread.  When that didn't work, I passed the worker thread
a pointer to the GTK main window, so that the worker thread could update the
progress bar directly.  I tried a tight loop (with very fine updates) and a
"looser" loop (which uses coarser updates but sleeps for a second, in
between them).  However, I see exactly the same problem, no matter what
strategy I use.

A couple of things occured to me...  firstly, I'm building using Visual
Studio 2005 (VC++8).  The documentation says not to use anything higher than
VC++6 (which has been obsolete for 10 years).  I could probably dig out
VC++6 though, if anyone thinks that might help.

The second thing is that I've based my main window on Gtk::Window.  If I'd
been using MFC I would probably have needed to base it on a CDialog.  Should
I have used Gtk::Dialog as my base class, instead of Gtk::Window?

If all else fails, can anyone point me in the direction of  a sample app
that shows how to implement a progress bar using gtk-win32?

Thanks,

John