ScottPlot Version: (What NuGet package are you using?)

• Platform: WinUI 3
• ScottPlot.WinUI 5.0.55

Issue:
When using transparent backgrounds in WinUI 3, applying any IAxisRule (SquareZoomOut, SquarePreserveX, SquarePreserveY, AutoSquare from #5021) causes plot frames to accumulate instead of being properly cleared.

Reproduction:

1. Set plot.FigureBackground.Color = ScottPlot.Colors.Transparent
2. Apply any IAxisRule → Frame accumulation occurs immediately
3. Same rules work perfectly with solid backgrounds

Expected: Clean single plot rendering
Actual: Two overlapping plot frames visible

Evidence:

• Solid background + IAxisRule: Works perfectly
• Transparent background + IAxisRule: Frame accumulation
• Transparent background + no rules: Works fine

Sample Project: [Attached WinUI3 project demonstrating the issue]
SquareOptimal.zip

After launch, selecting "SquarePreserveX" immediately produces the following double rendering:

Questions:

1. Is this a known limitation of transparent rendering with square axis rules? (Tested on WinUI3, but likely affects WPF as well)
2. What would be the recommended workaround for transparent backgrounds with axis rules?