Handle bad state, if an event is missing

src/gui/inputdevices/InputSequence.cpp

@@ -48,6 +48,9 @@ InputSequence::~InputSequence()
 	}
 	clearAxes();
 
+	// Make 100% sure there is no input running
+	stopInput();
+
 	XOJ_RELEASE_TYPE(InputSequence);
 }
 
@@ -354,6 +357,42 @@ bool InputSequence::actionStart()
 	return false;
 }
 
+
+/**
+ * Check if input is still running, or if there an event was missed
+ *
+ * @return true if input is stopped now
+ */
+bool InputSequence::checkStillRunning()
+{
+	if (!inputRunning)
+	{
+		// Already stopped
+		return true;
+	}
+
+	GdkModifierType mask = (GdkModifierType) 0;
+	GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(inputHandler->getXournal()));
+	gdk_device_get_state(device, window, NULL, &mask);
+
+	if ((GDK_BUTTON1_MASK & mask) ||
+		(GDK_BUTTON2_MASK & mask) ||
+		(GDK_BUTTON3_MASK & mask) ||
+		(GDK_BUTTON4_MASK & mask) ||
+		(GDK_BUTTON5_MASK & mask))
+	{
+		// Button still down
+		// Input is still running, probably everything OK
+		return false;
+	}
+
+	// Button is not down, stop input now!
+	// So the new input can start
+	actionEnd();
+
+	return true;
+}
+
 /**
  * Mouse / Pen up / touch end
  */

src/gui/inputdevices/InputSequence.h

@@ -43,12 +43,18 @@ public:
 	 */
 	void actionEnd();
 
+	/**
+	 * Check if input is still running, or if there an event was missed
+	 *
+	 * @return true if input is stopped now
+	 */
+	bool checkStillRunning();
+
 	/**
 	 * Set current input device
 	 */
 	void setDevice(GdkDevice* device);
 
-
 	/**
 	 * Clear the last stored axes
 	 */

src/gui/inputdevices/NewGtkInputDevice.cpp

@@ -69,11 +69,27 @@ bool NewGtkInputDevice::startInput(InputSequence* input)
 {
 	XOJ_CHECK_TYPE(NewGtkInputDevice);
 
+	if (inputRunning == input)
+	{
+		g_warning("Input for the same device started twice!");
+		return true;
+	}
+
+
 	if (inputRunning == NULL)
 	{
 		inputRunning = input;
 		return true;
 	}
+	else
+	{
+		if (inputRunning->checkStillRunning())
+		{
+			g_warning("Input was not stopped correctly!");
+			inputRunning = input;
+			return true;
+		}
+	}
 
 	return false;
 }