Fix color widget opens in wrong panel (fix #15705)

(cherry-picked from 721d3c5)

Author: nyalldawson

src/gui/qgspanelwidget.cpp

@@ -55,6 +55,13 @@ QgsPanelWidget*QgsPanelWidget::findParentPanel( QWidget* widget )
     if ( QgsPanelWidget* panel = qobject_cast< QgsPanelWidget* >( p ) )
       return panel;
 
+    if ( p->window() == p )
+    {
+      // break on encountering a window - eg a dialog opened from a panel should not inline
+      // widgets inside the parent panel
+      return nullptr;
+    }
+
     p = p->parentWidget();
   }
   return nullptr;

tests/src/python/test_qgspanelwidget.py

@@ -14,7 +14,7 @@
 
 import qgis  # NOQA
 
-from qgis.PyQt.QtWidgets import QWidget
+from qgis.PyQt.QtWidgets import QWidget, QDialog
 from qgis.gui import QgsPanelWidget
 from qgis.testing import start_app, unittest
 
@@ -49,6 +49,12 @@ def testFindParentPanel(self):
         w5 = QWidget(w4)
         self.assertEqual(QgsPanelWidget.findParentPanel(w5), w3)
 
+        # chain should be broken when a new window is encountered
+        n = QgsPanelWidget()
+        n2 = QDialog(n)
+        n3 = QWidget(n2)
+        self.assertFalse(QgsPanelWidget.findParentPanel(n3))
+
 
 if __name__ == '__main__':
     unittest.main()