gsk: Add GSK_RENDERING_MODE=full-redraw
Forces a full redraw every frame. This is done generically, so it's supported on every renderer. For widget-factory first page (with the spinner spinning and progressbar pulsing), I get these numbers per frame: action clipped full redraw snapshot 0ms 7-10ms cairo rendering 0ms 10-15ms Vulkan rendering 3-5ms 18-20ms Vulkan expected * 0ms 1-2ms GL rendering unsupported 55-62ms * expected means disabling rendering of unsupported render nodes, instead of doing fallback drawing. So it overestimates the performance, because borders and box-shadows are disabled.
Showing with 22 additions and 3 deletions