I'm using buttons 3 & 4 to switch spaces left/right, and often want to use it to move a window quickly to another space, so I left click+hold on a window title bar and click button 3 or 4 to move space. If button 3 or 4 is pressed too quickly the OS treats it as a double-click and minimises the window after moving space.
Normal mouse
Device information:
MacBook Pro 15" Retina Late-2013
- macOS version: 10.14.6
- BetterTouchTool version: 3.402 (1633)
Additional information (e.g. StackTraces, related issues, screenshots, workarounds, etc.):
It's possible to avoid the behaviour by waiting a second after dragging the window before moving space but it's very easy to forget to do that.