Feedback to the user, while executing long python script


I am a fire officer and the main developer for the BlenderFDS addon to Blender (, an open user interface for the NIST Fire Dynamics Simulator.

It can take a lot of time to export Blender geometry to FDS input file (2 or 3 minutes). During this time the Blender interface freezes and the user has no clue of what is going on.

1 - Is there something like Blender 2.4 Window.WaitCursor for Blender 2.5?
2 - Is it possible to use the progress indicator in addons (like that used during rendering operations)? How?
3 - If the previous questions have no answer, how can I notify the user that she just has to wait while Blender is working?

I thank you in advance.
Best regards,
Emanuele Gissi

I tried displaying “Wait please!” text on the 3dView with the blf module. No success…
It seems to me that it works in modal mode only. Isn’t it?


I tried:{“INFO”}, “Wait, please!”).
But the info message is queued and displayed at the end, when the script is over.
So no clue for the user during execution…