[galaxy-user] How to get random region of 1000-bp window in the chromosome not overlapping specific [gtf] file

Dear Galaxy develop team: As the subject said, I need to obtain random regions which are 1000-bb, and then filter these regions to remove regions overlapping a specific [gtf] file. So can I obtain random regions with Galaxy? I found (Regional Variation)->Make windows may help me, but the tool doesn't work at random. bests John