Since Combo and ListBox only read and display the list of items, they
should not modify the pointers inside the array of pointers passed in.
Adding "const" here makes it possible to call these functions with such
an array of const pointers. Previously, a cast to "const char**" was
required as a workaround, otherwise there was a compile error.
the inputlayout incorrectly described the POSITION attribute as being
4D, while ImDrawVert::pos is 2D. This went unnoticed because the buffer
binding has a stride of sizeof(ImDrawVert) and the POSITION is treated
as a float2 in the vertex shader. If you switch POSITION to float4 in
the vertex shader (and actually use the z/w in the matrix
multiplication) then everything become wacky-looking since it's
interpreting the texture coordinates as z/w. On a similar note: It's
weird that the projection matrix takes z and w into consideration when
those don't exist in the shader due to positions being float2s.
Nicolas Guillemot