hey mickey, thanks for using the extension!
support for the function "ImGui.Combo" is deprecated in imgui itself, so I opted to not add a wrapper for it. fortunately, you can use the new "ImGui.BeginCombo" along with "ImGui.EndCombo" to render more sophisticated and easier to manage combos
as for roadmaps, there isn't exactly a strong one established but there is a missing/unsupported features post on the github page