Clip rectangles in the command list can be inverted

[hexateron]

In certain cases the clip rectangle in the command lists can have the max bounds (z,w) less than the min bounds (x,y). In the OpenGL example, expand the "Child regions" section and scroll the "With borders" all the way down. Then expand the "Widgets" section. The column separator for the "With border" widget is not clipped properly:

In this case, a negative height is passed to glScissor, which causes an invalid value error (GL_INVALID_VALUE).

[ocornut]

Nice find! I didn't notice until now because the renderer I use doesn't use glScissor() and clip in another manner. That is to say, the application could skip the draw call - but the correct fix is that ImGui should clip the column itself earlier in the pipe. I'll work on that.

[ocornut]

I pushed a fix for the visual glitch.

Not 100% happy with the fix yet as the outer border for the window gets created into a vertex buffer and rendered, and then completely clipped. It should be discarded entirely so as not to waste a draw call for nothing. Will close the bug once it is fixed.

[ocornut]

Should be fixed now!