1 Create two stereo audio tracks, say five seconds each. 2 Zoom out a step. 3 Fit tracks to height if you can't see all of the lower track. F5 for Time Shift Tool. 4 Hover over the upper channel of the lower track and click/drag rightwards until the left edge of the track is after the end of the upper track. Without releasing the mouse, drag upwards. 5 On Mac and Linux, the track will almost certainly not move upwards, but will jump back to time zero. If you release mouse then repeat step 4, the incorrect behaviour will repeat. On Windows 10, I find this only happens about 50% of the time with my normal USB mouse, and hardly at all with NUMPAD mouse emulator. If on first attempt the track jumps back, on second attempt it will move up. 6 If at step 4 I drag from the lower channel, rightwards then up without mouse release, the drag always works on any platform. 7 If at step 4 I release the mouse when track 2 goes past track 1, then drag up from the upper channel, this always works on any platform. So does CTRL/COMMAND-drag after releasing mouse, and keeping mouse button down then moving the mouse into the lower channel before moving upwards. 8 If I change step 4 to drag the upper track after the end of the lower, the opposite problem occurs - the upper track is reluctant to drag down from the lower channel.

// See bug 1516