Combo: Added _NoMove flag to prevent window from docking, which has an effect in Docking branch (in Master was not noticeable as the Combo code kept repositioning the window). (#2835)

imgui_widgets.cpp

@@ -1505,8 +1505,10 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
             SetNextWindowPos(pos);
         }
 
+    // We don't use BeginPopupEx() solely because we have a custom name string, which we could make an argument to BeginPopupEx()
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_Popup | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoMove;
+
     // Horizontally align ourselves with the framed text
-    ImGuiWindowFlags window_flags = ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_Popup | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings;
     PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(style.FramePadding.x, style.WindowPadding.y));
     bool ret = Begin(name, NULL, window_flags);
     PopStyleVar();