Re: modify-frame-parameters with floating point offsets

[martin rudalics]

> No, the left external border is very small. Itʼs certainly not 20
> pixels wide.

Then it's possible that your window manager tries to optimize things
in various ways without telling you the whole story.  I can imagine
that if an external border is usually 20 pixels wide, a window manager
might decide that showing the entire border on the edge of the display
is of no use and move the window to some negative position.  I would
dislike such behavior because it would make it virtually impossible to
orderly tile the screen.  In either case you would have to look at the
sources of your window manager to tell what it really does.

martin