Merge branch 'master' into docking (will need further for io.AddFocusEvent)

# Conflicts:
#	backends/imgui_impl_glfw.cpp
#	backends/imgui_impl_opengl3.cpp
#	backends/imgui_impl_sdl.cpp
#	backends/imgui_impl_win32.cpp
#	imgui.cpp

imgui_demo.cpp

@@ -506,7 +506,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
         {
             HelpMarker(
                 "Those flags are set by the backends (imgui_impl_xxx files) to specify their capabilities.\n"
-                "Here we expose then as read-only fields to avoid breaking interactions with your backend.");
+                "Here we expose them as read-only fields to avoid breaking interactions with your backend.");
 
             // Make a local copy to avoid modifying actual backend flags.
             ImGuiBackendFlags backend_flags = io.BackendFlags;