Author: koying
[Added to the original trac issue at 5.19pm, Wednesday, 19th March 2008]

I assume that, with no background, you really mean hidden background, do you?
Because, with "Background - None", there is an infinite zoom.
Hiding the background keeps the projection (and limitations) from the tile provider, while the "None" background uses a custom projection.

Author: ColinMarquardt
[Added to the original trac issue at 6.03pm, Wednesday, 19th March 2008]

Oh, indeed, I had just hidden the background, not actually set it to None.
I must say that this is about the only thing that's holding me back from using Merkaartor as my only editor, since I mainly map stuff that requires a high zoom.

Author: koying
[Added to the original trac issue at 3.39pm, Saturday, 22nd March 2008]

(In [7138]) ADD : configurable projection type (allow custom zoom in "Merkaartor" projection, for background also). fixes #752