show a rotating circle when running a busy function

[hoffen]

Hi~

In my program I used a time-consumed function from dll, I show a picture before running into this function . I want the picture rotate to indicate a busy state,so I have to change its angle. I tried to use timer to add angle when timeout signal is emited , but I failed . Seems that during this busy function the signal can not be handled. but after this function ended, the picture starts to rotate... So what can I do? Shoud I use a thread to do this ? What's your suggestion?
Thanks in advance!

[wysota]

[wiki]Keeping the GUI Responsive[/wiki]