Added ResetMouseDragDelta() for iterative dragging operations

imgui.h

@@ -390,6 +390,7 @@ namespace ImGui
     IMGUI_API bool          IsPosHoveringAnyWindow(const ImVec2& pos);                          // is given position hovering any active imgui window
     IMGUI_API ImVec2        GetMousePos();                                                      // shortcut to ImGui::GetIO().MousePos provided by user, to be consistent with other calls
     IMGUI_API ImVec2        GetMouseDragDelta(int button = 0, float lock_threshold = -1.0f);    // dragging amount since clicking, also see: GetItemActiveDragDelta(). if lock_threshold < -1.0f uses io.MouseDraggingThreshold
+    IMGUI_API void          ResetMouseDragDelta(int button = 0);
     IMGUI_API ImGuiMouseCursor GetMouseCursor();                                                // get desired cursor type, reset in ImGui::NewFrame(), this updated during the frame. valid before Render(). If you use software rendering by setting io.MouseDrawCursor ImGui will render those for you
     IMGUI_API void          SetMouseCursor(ImGuiMouseCursor type);                              // set desired cursor type
     IMGUI_API float         GetTime();