This may be a design feature or a Bug....but in either case....
Suggest that all "global" settings made/selected remain selected/checked etc. for all future TFP uses...until changed by user
unless specifically changed in a file....and that stickiness sticks with the file (solid fill does stick with the file, which is good, but not sticky in the global program setting, which is bad)
Most choices seem to work that way but "solid fill" walls does not.
No matter how many times or under any circumstances (start-up, with or without file open, even with a file that has solid filled walls, upon close etc.) the "solid fill" choice always resets to no solid fill and must be selected/checked (except for opening a previously created file in which solid fill was selected before closing)