diff --git a/src/PlanView/PlanEditToolbar.qml b/src/PlanView/PlanEditToolbar.qml
index f3a837ca14932b1094e618eefae16617a9c75279..7822e41a583435b81cafcecc7a1a110b448592f4 100644
--- a/src/PlanView/PlanEditToolbar.qml
+++ b/src/PlanView/PlanEditToolbar.qml
@@ -8,7 +8,7 @@
  ****************************************************************************/
 
 import QtQuick              2.3
-import QtQuick.Controls     2.11
+import QtQuick.Controls     2.4
 import QtQuick.Layouts      1.2
 
 import QGroundControl               1.0
diff --git a/src/QmlControls/QGCComboBox.qml b/src/QmlControls/QGCComboBox.qml
index 5fcd19b8f83db83e38ec463b2affe3c306c73c3d..44bd0a2ab92c96ffc87e403348cdb44913b79468 100644
--- a/src/QmlControls/QGCComboBox.qml
+++ b/src/QmlControls/QGCComboBox.qml
@@ -8,10 +8,10 @@
  ****************************************************************************/
 
 import QtQuick                  2.11
-import QtQuick.Window           2.11
-import QtQuick.Controls         2.11
-import QtQuick.Controls.impl    2.11
-import QtQuick.Templates        2.11 as T
+import QtQuick.Window           2.3
+import QtQuick.Controls         2.4
+import QtQuick.Controls.impl    2.4
+import QtQuick.Templates        2.4 as T
 
 import QGroundControl.ScreenTools   1.0
 import QGroundControl.Palette       1.0
@@ -20,12 +20,11 @@ T.ComboBox {
     id:             control
     padding:        ScreenTools.comboBoxPadding
     spacing:        ScreenTools.defaultFontPixelWidth
-    implicitWidth:  Math.max(implicitBackgroundWidth + leftInset + rightInset,
-                             implicitContentWidth + leftPadding + rightPadding,
-                             sizeToContents ? _popupWidth : 0)
-    implicitHeight: Math.max(implicitBackgroundHeight + topInset + bottomInset,
-                             implicitContentHeight + topPadding + bottomPadding,
-                             implicitIndicatorHeight + topPadding + bottomPadding)
+    implicitWidth:  Math.max(background ? background.implicitWidth : 0,
+                            contentItem.implicitWidth + leftPadding + rightPadding)
+    implicitHeight: Math.max(background ? background.implicitHeight : 0,
+                             Math.max(contentItem.implicitHeight,
+                                      indicator ? indicator.implicitHeight : 0) + topPadding + bottomPadding)
     leftPadding:    padding + (!control.mirrored || !indicator || !indicator.visible ? 0 : indicator.width + spacing)
     rightPadding:   padding + (control.mirrored || !indicator || !indicator.visible ? 0 : indicator.width)