use current transparency to update effects

--the background contrast effect should be applied
only when the dock/panel is visually solid otherwise
it may block the transparency settings

BUG: 397431
FIXED-IN: v0.8.1

app/dock/dockview.cpp

@@ -1605,7 +1605,10 @@ void DockView::updateEffects()
         }
     } else if (m_behaveAsPlasmaPanel && m_drawEffects) {
         KWindowEffects::enableBlurBehind(winId(), true);
-        KWindowEffects::enableBackgroundContrast(winId(), m_theme.backgroundContrastEnabled(),
+
+        bool drawBackgroundEffect = m_theme.backgroundContrastEnabled() && (m_dockTransparency == 100);
+
+        KWindowEffects::enableBackgroundContrast(winId(), drawBackgroundEffect,
                 m_theme.backgroundContrast(),
                 m_theme.backgroundIntensity(),
                 m_theme.backgroundSaturation());

containment/package/contents/ui/PanelBox.qml

@@ -309,6 +309,12 @@ Item{
             Component.onCompleted: root.updateEffectsArea.connect(updateEffectsArea);
             Component.onDestruction: root.updateEffectsArea.disconnect(updateEffectsArea);
 
+            Binding{
+                target: root
+                property: "currentPanelTransparency"
+                value: solidBackground.opacity * 100
+            }
+
             Connections{
                 target: root
 

containment/package/contents/ui/VisibilityManager.qml

@@ -106,7 +106,7 @@ Item{
         target: dock
         property: "dockTransparency"
         when: dock
-        value: root.panelTransparency
+        value: root.currentPanelTransparency
     }
 
     Binding{

containment/package/contents/ui/main.qml

@@ -187,7 +187,9 @@ DragDrop.DropArea {
     property int modifierClick: plasmoid.configuration.modifierClick
 
     property int panelEdgeSpacing: Math.max(panelBoxBackground.lengthMargins, 1.5*appShadowSize)
-    property int panelTransparency: plasmoid.configuration.panelTransparency
+    property int panelTransparency: plasmoid.configuration.panelTransparency //user set
+    property int currentPanelTransparency: 0 //application override
+
     property bool panelShadowsActive: (( (plasmoid.configuration.panelShadows && !root.backgroundOnlyOnMaximized)
                                         || (plasmoid.configuration.panelShadows &&  root.backgroundOnlyOnMaximized && !root.forceTransparentPanel))
                                        && !(disablePanelShadowMaximized && dock.visibility.existsWindowMaximized))