protect floating views appearance

--floating views is a strange situation for which
plasma theme do not have any way to be protected for
their drawing (there is a chance that shadows and content
overlap). Latte in order to protect from that situation
now uses the auto-discovered plasma theme roundness to be used
in order to calculate the minimum thicknes for panel
background.

containment/package/contents/ui/PanelBox.qml

@@ -458,23 +458,55 @@ Item{
                 }
             }
 
+            Binding {
+                target: root
+                property: "panelThickMarginBase"
+                value: {
+                    var minimum = root.screenEdgeMarginEnabled && themeExtended ? themeExtended.topEdgeRoundness : 0;
+
+                    if (root.useThemePanel){
+                        if (root.isVertical){
+                            if (plasmoid.location === PlasmaCore.Types.LeftEdge) {
+                                return Math.max(minimum, solidBackground.margins.left);
+                            } else if (plasmoid.location === PlasmaCore.Types.RightEdge) {
+                                return Math.max(minimum, solidBackground.margins.right);
+                            }
+                        } else {
+                            if (plasmoid.location === PlasmaCore.Types.BottomEdge) {
+                                return Math.max(minimum, solidBackground.margins.bottom);
+                            } else if (plasmoid.location === PlasmaCore.Types.TopEdge) {
+                                return Math.max(minimum, solidBackground.margins.top);
+                            }
+                        }
+                    } else {
+                        return 0;
+                    }
+                }
+            }
+
             Binding {
                 target: root
                 property: "panelThickMarginHigh"
                 value: {
+                    var minimum = root.screenEdgeMarginEnabled && themeExtended ? themeExtended.topEdgeRoundness : 0;
+
                     if (root.useThemePanel){
                         if (root.isVertical){
-                            if (plasmoid.location === PlasmaCore.Types.LeftEdge)
+                            if (plasmoid.location === PlasmaCore.Types.LeftEdge) {
-                                return solidBackground.margins.right;
+                                return Math.max(minimum, solidBackground.margins.right);
-                            else if (plasmoid.location === PlasmaCore.Types.RightEdge)
+                            } else if (plasmoid.location === PlasmaCore.Types.RightEdge) {
-                                return solidBackground.margins.left;
+                                return Math.max(minimum, solidBackground.margins.left);
+                            }
                         } else {
-                            if (plasmoid.location === PlasmaCore.Types.BottomEdge)
+                            if (plasmoid.location === PlasmaCore.Types.BottomEdge) {
-                                return solidBackground.margins.top;
+                                return Math.max(minimum, solidBackground.margins.top);
-                            else if (plasmoid.location === PlasmaCore.Types.TopEdge)
+                            } else if (plasmoid.location === PlasmaCore.Types.TopEdge) {
-                                return solidBackground.margins.bottom;
+                                return Math.max(minimum, solidBackground.margins.bottom);
                             }
                         }
+                    } else {
+                        return 0;
+                    }
                 }
             }
 

containment/package/contents/ui/main.qml

@@ -384,7 +384,7 @@ Item {
     }
 
     property int themePanelThickness: {
-        var panelBase = root.panelThickMarginHigh;
+        var panelBase = root.panelThickMarginHigh + root.panelThickMarginBase;
         var margin = shrinkThickMargins ? 0 : thickMargins + localScreenEdgeMargin;
         var maxPanelSize = (iconSize + margin) - panelBase;
         var percentage = Latte.WindowSystem.compositingActive ? plasmoid.configuration.panelSize/100 : 1;