selfImDrawList handle on which this method operates.
aTop-left corner of the rectangle in absolute screen coordinates.
bBottom-right corner of the rectangle in absolute screen coordinates.
uv_aTexture UV coordinates for the corresponding vertex.
uv_bTexture UV coordinates for the corresponding vertex.
colPacked ImU32 RGBA color; alpha controls opacity.
Write an axis-aligned rectangle with UVs into pre-reserved vertex and index space.