How to constrain area redrawing to clip region?

Hi,

I built this game, [Glimmer Tetris](https://github.com/AndyObtiva/glimmer-dsl-libui#tetris)

It runs fast with a basic 2D look (each block is a path).


When I attempt to add a simulated bevel-block 3D look via 4 extra polygons per block where each polygon is a figure of multiple line calls done under a single path (similar to the [Glimmer Tetris built with SWT](https://github.com/AndyObtiva/glimmer_tetris))...


Area redrawing slows down to a crawl!

I ensured that only a single redraw is happening per movement of the Tetris tetromino blocks.

My question is: I could probably optimize performance by asking the area to redraw only the blocks that changed instead of the entire playfield.

How do I do that with libui? Is that option available? The only thing I saw is queueRedrawAll, which redraws everything.

Is that what save and restore are all about? Initial saving... restoring the whole area, making a small change, and then saving again? Does that improve performance?

If clipped redrawing is not available, this would be a great performance optimization feature to have I think.