Editor: Allow selecting a group of whitespaces with double click

Fixes: QTCREATORBUG-24607
Change-Id: I993e2c3a8f1054fc6787cca8e22704fb5b2ab9d1
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -5493,7 +5493,30 @@ void TextEditorWidget::mouseDoubleClickEvent(QMouseEvent *e)
         }
     }
 
+    QTextCursor oldCursor = multiTextCursor().mainCursor();
+    const int oldPosition = oldCursor.position();
+
     QPlainTextEdit::mouseDoubleClickEvent(e);
+
+    // QPlainTextEdit::mouseDoubleClickEvent just selects the word under the text cursor. If the
+    // event is triggered on a position that is inbetween two whitespaces this event selects the
+    // previous word or nothing if the whitespaces are at the block start. Replace this behavior
+    // with selecting the whitespaces starting from the previous word end to the next word.
+    const QChar character = characterAt(oldPosition);
+    const QChar prevCharacter = characterAt(oldPosition - 1);
+
+    if (character.isSpace() && prevCharacter.isSpace()) {
+        if (prevCharacter != QChar::ParagraphSeparator) {
+            oldCursor.movePosition(QTextCursor::PreviousWord);
+            oldCursor.movePosition(QTextCursor::EndOfWord);
+        } else if (character == QChar::ParagraphSeparator) {
+            return; // no special handling for empty lines
+        }
+        oldCursor.movePosition(QTextCursor::NextWord, QTextCursor::KeepAnchor);
+        MultiTextCursor cursor = multiTextCursor();
+        cursor.replaceMainCursor(oldCursor);
+        setMultiTextCursor(cursor);
+    }
 }
 
 void TextEditorWidgetPrivate::setClipboardSelection()