Ensure correct mouse position for double click.

1 files changed, 20 insertions, 17 deletions

diff --git a/c/layout.h b/c/layout.h
index 3d9cc3b..29647e2 100644
--- a/c/layout.h
+++ b/c/layout.h
@@ -21,18 +21,19 @@ struct Dragger
 	bool HandleLButtonDown();
 	bool HandleSetCursor();
 protected:
-	bool IsDown();
-	bool IsDouble();
-	virtual bool InDragArea(int x, int y);
+	bool IsDown() const;
+	bool IsDouble(const long time, const POINT& pt);
+	virtual bool InDragArea(int x, int y) const;
 	/* Perform drag, resizing relevant windows. */
-	virtual void Drag(int x, int y);
+	virtual void Drag(int x, int y) const;
 	/* Reset dragger to automatic position. */
-	virtual void Reset();
+	virtual void Reset() const;
 	/* Called after drag, when mouse button is released. */
-	virtual void Done();
+	virtual void Done() const;
 private:
 	bool m_bActive = false;
-	long m_time = 0;
+	long m_time0 = 0;
+	POINT m_pt0 = {0, 0};
 };
 
 /* DlvDragger implements the draggable split between the data list
@@ -41,24 +42,26 @@ private:
 struct DlvDragger : public Dragger
 {
 private:
-	bool InDragArea(int x, int y) override;
-	void Drag(int x, int y) override;
-	void Reset() override;
-	void Done() override;
+	bool InDragArea(int x, int y) const override;
+	void Drag(int x, int y) const override;
+	void Reset() const override;
+	void Done() const override;
 };
 
 /* Below follows the implementation of the non-virtual member
  * functions of Dragger, on which derived objects rely. */
 
-inline bool Dragger::IsDouble()
+inline bool Dragger::IsDouble(const long time, const POINT& pt)
 {
-	const long time = GetMessageTime();
-	const bool dbl = time-m_time <= static_cast<long>(GetDoubleClickTime());
-	m_time = time;
+	const bool dbl = time-m_time0 <= static_cast<long>(GetDoubleClickTime())
+	&& abs(pt.x-m_pt0.x) <= Metric<SM_CXDOUBLECLK>
+	&& abs(pt.y-m_pt0.y) <= Metric<SM_CYDOUBLECLK>;
+	m_time0 = time;
+	m_pt0 = std::move(pt);
 	return dbl;
 }
 
-inline bool Dragger::IsDown()
+inline bool Dragger::IsDown() const
 {
 	return GetKeyState(VK_LBUTTON) & 0x8000;
 }
@@ -70,7 +73,7 @@ inline bool Dragger::HandleLButtonDown()
 	Require(GetRelativeCursorPos(g_hWnd, &pt));
 	if (!InDragArea(pt.x, pt.y)) return false;
 
-	if (IsDouble()) {
+	if (IsDouble(GetMessageTime(), pt)) {
 		m_bActive = false;
 		Reset();
 	} else