Numbers greater than INT_MAX currently behave strangely. Instead of incrementing the number they return 0 for num and add .
Misses an important point that the name is incremented to the next unused file, never overwriting existing files.
This could be removed? (as far as I can see this isn't used), if it is used it could follow the operator name. Save Blender File (Incremental).
picky avoiding int-overflow be done at the same time as avoiding too many attempts.
Use enabled otherwise this is still clickable (which isn't expected for greyed out menu items).
Use ED_region_panel_category_gutter_isect_xy or add a new public utility function to area_query.c if existing functions cannot be used - with an explanation for how it differs from existing intersection checking functions.
Include a comment for shy checking CTRL is needed, also shouldn't this check event->modifier == KM_CTRL (so other modifier combinations are ignored).
In general this works well, however I'd prefer to support undo in a way that's closer to how buttons work (where the information for undo is automatically extracted).
Use win->eventstate, win->event_last_handled is intended for event handling logic and not to be used by interface logic. Updated the doc-string to note this 09ba0210d9a19a2713fa0f92cf5f54914789c62f.
@HooglyBoogly I'll check on this, if it's simply the compacting the array that's slow, I'll check on optimizing this.