Fix preview mouse position on Windows

[yocox]

1. Fix preview mouse position on Windows On Windows, if the screen resize is not 1, the device resolution might be different from the mouse resolution.

The "touch_down" and "touch_up" event use the device resolution, but the "on_mouse_pos" event use the mouse resolution. So the mouse position is not correct. We need to convert the mouse position to the device resolution.

2. Improve performance of find preview.