Improve behavior of object selection

[moshee]

SUMMARY

I often find myself having the following troubles:

1. Drag selection selects more items than I want. LibrePCB only seems to support overlap mode in drag/marquee select.
2. I have to try multiple times to click/drag something because the draggable area is not visible and are often unexpectedly small (example: pins only draggable by the tip)

Object selection is one of the fundamental activities in CAD drafting. Allowing more options for selecting objects will improve efficiency.

SOLUTION

1. In many CAD programs, one can switch between overlap and cover selection modes by using either the drag direction (common in MCAD) or a modifier key (I think Altium does this - it's cover by default and can do overlap by holding Alt).
2. Highlighting a component in some way when the cursor is within its draggable hitbox will make selecting individual objects more efficient by providing visual feedback to the cursor positioning loop.
3. A longer-term goal would be to additionally implement selection filters so that selection can be limited to certain types of objects. Ideally this would be implemented with a checklist (like Altium) and NOT a dropdown (like Mentor).

[dbrgn]

Although it's not very intuitive / discoverable, I like using the drag direction for selection mode. Lightburn uses that as well.