redraw at schematic block move

[Novak Tamas]

When moving a block in eechema, block in its original place is still visible while new block is moving. It may seem to be a "feature" (to compare the new position to the original one), but old block is not redrawn after changing zoom factor.
And not a big deal (it seldom happens) but moving large block is painfully slow even on high-end CPU/GPU machines. Some optimization would be fine even if not using h/w acceleration.

[Jeff Young (jeyjey)]

(The performance issues are because eeschema is still on the legacy canvas -- ie: no hardware acceleration. Moving eeschema to the GAL canvas will be the main focus of 6.0.)

[Novak Tamas (novak-7)]

I think this bug is not exactly the same...although if someone works on #1740138 duplicate block issue, he may correct the Move block function as well.

If switching eeschema to OpenGL is on the horizon, working on optimization of block moving is really unnecessary, despite of seeming unduly slow --even without hardware acceleration.