Fix: Drag items slowly

[GraceDM]

Describe the new feature you would like to see in Seamly

I'm not too sure which section this fits into since it's a behaviour problem.

When dragging a point label or a pattern piece, a sudden move can make the item zip out of the current view and way out of the area. Is it possible to slow down the drag movement?

[Onetchou]

The PR #1156 I just created partly addresses that issue. It's not truly slowing down the automatic drag movement, but it makes this auto-drag movement only dependent on the position of the mouse. The automatic pan of the screen is then much less random, it should avoids the sudden movement of the pieces when they are moved 😊

[GraceDM]

Oooh, thank you very much. I'll be sure to check it out.