Excellent info! I was not aware of the tooltip info function in TYPViewer, always too quick maybe.
This explains also the behaviour of some thin bitmap lines sometimes not displaying good when in certain angles in relation to the pixels of the display maybe. I will do some experimenting with this and the checkbox "Wide Tool/Thin Tool" in MPC.
I have not used mkgmap but I can see good documentation of the TYP file structure there, more to read then...