Bug: Mouse won't "let go" of objects with lots of connections

Often I'll grab an object or a group of them to move them around, and if I move them outside the window and let go of the mouse, they'll "stick" to the mouse and I can't let them go. But it also happens if I move them outside and bring them back. It's been a minor annoyance before, but it's getting much more so with bigger patches.

It doesn't happen when moving objects with arrow keys, and it doesn't seem to happen if Connections are hidden, or if there aren't many of them. Once there's a lot of connections, though, it's pretty consistent. The only way to get out of it is to click a lot, right-click, tap Control etc., it's pretty chaotic but will eventually give the context menu, and the objects are no longer stuck. It's definitely something to do with moving out of the patch window and then back, doesn't seem to happen if I stay within the screen, no matter how many connections there are.

XP, 5.1.1, though it's been happening for awhile. Any thoughts?