Hey, so I know this forum is a few months old, but found myself here because I was experiencing the same issue. This "gluing", or in my case, difficulty selecting lines/shapes within surrounding, or larger, lines/shapes happened a lot when I was using different colors to make "doors" or "secret passageways". My issues arose from not getting the mouse cursor to recognize a specific dynamic lighting piece while hovering my pointer over it. I then had to use the select box (click and drag) to "grab" the line. No matter how small I made this box it still seemed to grab a large portion of the map lines/shapes at the same time and my "door" became permanently attached to other drawings. After a lot of frustration and searching I found that it matters a lot what level of zoom you're currently on. As I spend a lot of time at 50% or less when building maps, I never tried changing the zoom to see if it affected line/shape selection. It Does. I don't know for sure where the "sweet spot" is, but 100% seemed to work for most pieces. I was able to select my "doors" pretty much every time. For example, while in play I need to zoom in to 100% remove a door my PCs walk through, then zoom back out to whatever % fits the situation. I don't know if this will be helpful, but I figured I would try and contribute to the unanswered question.