I think it looks okay.. but sometimes I don't notice display stretching much when it's present.
1680x1050 widescreen here. 16:10. I got black bars at the top and bottom, and the corner markers at the corners of the visible area.
Not related to the uploaded cap:
I messed around with altering layer zooming and placing black bars, but it's odd. Setting the layer zoom isn't working right unless I press Z twice.
That is, my event is:
MouseKeyboard: On key Z pressed
System Change display size to 640 x 480
Set Layer "Layer 1" zoom ratio to (640/1440 * 100, 480/900 * 100)
or even if I replace that set layer zoom ratio with
Set Layer "Layer 1" zoom ratio to (44, 53)
I have to press Z twice.
The first time, it becomes 70.3125, 70.3215.
I have an event afterward telling me what the zoom is:
System: Always (every tick)
Text Set text to "" & DisplayWidth & "x" & DisplayHeight & ", Zoom: " & LayerZoomX("Layer 1") & "x" & LayerZoomY("Layer 1")
I used 1440x900 so I could test the zoom in windowed mode.