Electric panel distance from windows and/or gas service entry
As far as the electrical equipment goes there is nothing beyond the working clearances. The equipment can be directly adjacent to either item.

Working clearance for a panel is 30" wide and 36" deep (in front). The equipment can be anywhere in the 30" wide space.

There may be a gas code clearance issue, but I am not familiar with that code. 

Might I ask why you are asking?