Transparent bitmap (bmp)

[stratocast]

After posting (erroneously ) to the "export to precise dimentions without constaining proportions" thread. I was playing about with exporting drawings.

I created some shapes, stuck a rectangle behind (no outline, no fill), selected the rectangle only and exported to see what I would get with different formats. When I exported to bitmap (bmp), without changing anything in the export dialog, lo and behold, I got a TRANSPARENT bmp file. What the ....! Bmp doesn't support transparency, right.

First of all, I thought that it was actually a png or gif that had somehow been saved with the wrong extension. But when I changed the extension and tried to open it, Irfanview told me that it was indeed a bmp.

I cannot envisage any possible application for this, it's interesting though.