Making it so mouse interaction only tracks one mouse button at a time.

So if you the user is dragging with a middle mouse button, then right and left clicks are ignored.
Fixes (long standing) issue #192 ... I hope!

src/TextArea.cpp

@@ -1102,6 +1102,11 @@ void TextArea::focusOutEvent(QFocusEvent *event) {
  * @param event
  */
 void TextArea::contextMenuEvent(QContextMenuEvent *event) {
+
+    if (mouseButtonState_ != Qt::MouseButton::NoButton) {
+        return;
+    }
+
 	if (event->modifiers() != Qt::ControlModifier) {
 		Q_EMIT customContextMenuRequested(mapToGlobal(event->pos()));
 	}
@@ -1185,6 +1190,11 @@ void TextArea::keyPressEvent(QKeyEvent *event) {
  */
 void TextArea::mouseDoubleClickEvent(QMouseEvent *event) {
 	if (event->button() == Qt::LeftButton) {
+
+        if (mouseButtonState_ != Qt::MouseButton::NoButton) {
+            return;
+        }
+
 		if (!clickTracker(event, /*inDoubleClickHandler=*/true)) {
 			return;
 		}
@@ -1261,6 +1271,14 @@ void TextArea::mouseMoveEvent(QMouseEvent *event) {
  */
 void TextArea::mousePressEvent(QMouseEvent *event) {
 
+    // only accept one mouse button press at a time
+    if (mouseButtonState_ != Qt::MouseButton::NoButton) {
+        return;
+    }
+
+    mouseButtonState_ = event->button();
+
+
 	if (event->button() == Qt::LeftButton) {
 		switch (event->modifiers() & (Qt::ShiftModifier | Qt::ControlModifier | Qt::AltModifier | Qt::MetaModifier)) {
 		case Qt::ShiftModifier | Qt::ControlModifier:
@@ -1323,13 +1341,24 @@ void TextArea::mousePressEvent(QMouseEvent *event) {
  */
 void TextArea::mouseReleaseEvent(QMouseEvent *event) {
 
+    // ignore key ups from buttons not currently known to be pressed
+    if(mouseButtonState_ != event->button()) {
+        return;
+    }
+
+    mouseButtonState_ = Qt::MouseButton::NoButton;
+
 	switch (event->button()) {
 	case Qt::LeftButton:
-		endDrag();
+        if(dragState_ == PRIMARY_CLICKED) {
+            endDrag();
+        }
 		break;
+
 	case Qt::RightButton:
 		endDrag();
 		break;
+
 	case Qt::MiddleButton:
 		switch (event->modifiers() & (Qt::ShiftModifier | Qt::ControlModifier | Qt::AltModifier | Qt::MetaModifier)) {
 		case Qt::ControlModifier:
@@ -1350,6 +1379,7 @@ void TextArea::mouseReleaseEvent(QMouseEvent *event) {
 			break;
 		}
 		break;
+
 	default:
 		break;
 	}

src/TextArea.h

@@ -437,6 +437,7 @@ private Q_SLOTS:
 	int64_t rectAnchor_                            = 0; // Anchor for rectangular drag operations
 	int wrapMargin_                                = 0;
 	void *highlightCBArg_                          = nullptr; // Arg to unfinishedHighlightCB
+	Qt::MouseButton mouseButtonState_              = Qt::MouseButton::NoButton;
 
 private:
 	BlockDragTypes dragType_; // style of block drag operation