blocking and unblocking signals

[Kees Kling <ckling upcmail nl>]

Hi,

I wrote a drawingArea in which I do a complex drawing. To update the 
area takes about 2-3 seconds, so after panning/zooming I create a 
display I draw a temporary image and after that i recreate the new 
drawing. This recreation is done in an on_Idle function. If I connect 
the on_Idle function in the widget constructor, the application uses a 
lot of CPU. Next step was to connect and block the connection in the 
constructor and when needed to unblock it till the update is done. 
Blocking works, but I unblocking doesn't

2 questions:     Why does unblock not work.
                        Is it a good practice to do the updating or is 
there another way

Regards

Kees Kling