Describe the bug
When scale≠100%, image moved with mouse unexpectedly after holding shift to drag window.

To Reproduce
Steps to reproduce the behavior:
Version: PicView-v3.2-win-x64

1. Resize scale ≠ 100%;
2. Hold shift and drag the window;
3. Release shift key and mouse left button;
4. Image would move with mouse without left button holding unexpectedly.

Screenshots
A video to reproduce this bug: bug.mp4