@janx said:
This could be made also as option to Eraser. For example, with holding ctrl+alt+mouse I select lines must be collapsed and with releasing they collapse at average point. If selected lines/goups of lines are not connected with each other, they collapse in their own average point. Anyway, for comfortable use it must be tool which You can shortcut on keyboard.
you can already do this with vertex tools (though there's no eraser involved.)
using vertex tool's select tool (various window select options which work in combination with a normal click for a single vertex), just go around selecting all the vertices you want to collapse then 'merge vertices'
it doesn't matter how close or far they are apart or if there are unselected vertices in between selected vertices..
the 'merge close vertices' feature you saw in the video is a different feature in which you can select a larger group of vertices then filter their merge behavior depending on the distance between them..
[as in-- everything you seem to be asking for is already available in vertex tools.. (but hey, i could be missing something?)]
[well, you can't select lines per se.. you have to select the vertexes on each end]