Misc tweaks/fixes (see details).

Combo: ultra minor fix for popup positioning policy mismatch depending on ImGuiComboFlags_PopupAlignLeft flag.
Made ImHashXXX functions return ImGuiID.
IsWindowNavFocusable use !WasActive.. it worked because it was only called in NewFrame()->NavUpdate() before the transition loop + EndFrame() only.
Fix unused variable warning.
4 files changed