"Snapper" for italic angle possible?

There is a “snapper” for moving along the horizontal and vertical. Would be nice to have one for the italic angle…

I’m not about what you mean by “Snapper” but maybe check “Move Selection … at Italic Angle” script by Daniel Gamage

the cursor is not on the image, sorry.

If you move a point or an anchor, a thin line appears and the anchor is forced a little bit to move along this line. Or is this a plug in?

Script is good, thantks, but an italic angle option for this feature would be much better!

These are magnetic guides. I like the idea of adhering to the italic angle, but the vertical is also useful and if both vertical and italic guides are active, they may conflict with each other. Still, interesting idea worth looking into.

A modifier key? It seems, only shift is in use while dragging points or anchors…

By the way, what exactly does the escape key during drag? It produces very strange behaviour and Glyphs finaly crashed…