Desk.cpl screensaver preview got smaller, an optimization challenge

During 0.4.15-dev'ing, the screensaver preview rectangle shrank in size.
It might have been caused by this commit 0.4.15-dev-5140-g092fc8e or by a commit nearby. Doesn't matter actually.

Although drawing within the monitor bmp was a noble goal I guess, I still preferred the bigger preview that we had before, because it gave better rendering quality of the preview.

Here is a comparison.PNG which proves that XPSP3 gives a bigger preview rectangle.

Increasing the preview again would now most likely require us to replace the monitors bmp.
And here comes the optimization challenge:
I do request that to happen without increasing the monitor.bmp bitmaps binary size, which is currently 20.278bytes.
reducing color depth is allowed
using fancy compression is allowed
programatically creating the monitor is allowed
scaling is allowed, as long as the result is visually appealing, not the preferred solution though
increasing the cpls binary or bitmap size is not allowed, so please do not just use a bigger monitor.bmp

To justify my spleen about binary size:
XPSP3 desk.cpl binary size is just 138.240 Bytes
ros desk.cpl of GCC8.4.0 dbg from 0.4.15-dev-5517-g9762ef9 is already 652.800byte
And even if rls config or MSVC builds are for sure a bit better here, they still already are much bigger than the MS version, I bet they are > 400.000 bytes already, no matter which compiler is used

Due to my challenging extra-conditions I do rate this a task with prio trivial just, instead of a bug+regression.