ID2D1RenderTarget::PushAxisAlignedClip/PopAxisAlignedClip used to clip the region (with wxGraphicsRenderer::Clip) and ID2D1RenderTarget::PushLayer/PopLayer used to rendering to the transparent layer (with wxGraphicsRenderer::BeginLayer) are non independent but have to be used in the controlled sequences: "A PushAxisAlignedClip and PopAxisAlignedClip pair can occur around or within a PushLayer and PopLayer, but cannot overlap" (and of course finally each Push* call must have a matching Pop* call).
To control the sequence of access to the AxisAlignedClips and Layers there is implemented a wxStack data member holding Clips/Layers parameters which reflects a physical stack of respective Clips/Layers in ID2D1RenderTarget. This way we know in which order to pop and what to pop from ID2D1RenderTarget stack if there is a need to do so.
Closes#17590