fix #961,Semi-Tranparent Panels at ImproveVisibility

--update issue #957 in order to take into account
semi-transparent panels. With semi-transparent panels
contrast could be a puzzle. The changes that
introduced with this patch are:
1. Enable Improve Visibility when also case [E] from
 #957 is enabled.
2. When a semi-transparent panel exists in combination
with Improve Visibility option then add a threshold
in order to indicate if the Colorizer will be applied
or not. The threshold is 40% in order to indicate if
a semi-transparent panel is solid or not.

containment/package/contents/ui/main.qml

@@ -85,6 +85,12 @@ DragDrop.DropArea {
     property bool disablePanelShadowMaximized: plasmoid.configuration.disablePanelShadowForMaximized && Latte.WindowSystem.compositingActive
     property bool drawShadowsExternal: panelShadowsActive && behaveAsPlasmaPanel && !visibilityManager.inTempHiding
     property bool editMode: editModeVisual.inEditMode
+    property bool windowIsTouching: dock && dock.visibility && (dock.visibility.existsWindowMaximized || dock.visibility.existsWindowSnapped || hasExpandedApplet)
+
+    property bool forceSemiTransparentPanel: ((!plasmoid.configuration.solidBackgroundForMaximized && plasmoid.configuration.backgroundOnlyOnMaximized && windowIsTouching)
+                                             || (plasmoid.configuration.solidBackgroundForMaximized && !plasmoid.configuration.backgroundOnlyOnMaximized && !windowIsTouching))
+                                             && Latte.WindowSystem.compositingActive
+
     property bool forceSolidPanel:  plasmoid.configuration.solidBackgroundForMaximized && dock && dock.visibility
                                     && Latte.WindowSystem.compositingActive
                                     &&(dock.visibility.existsWindowMaximized || dock.visibility.existsWindowSnapped || hasExpandedApplet)
@@ -93,7 +99,7 @@ DragDrop.DropArea {
                                          && Latte.WindowSystem.compositingActive
                                          && !(hasExpandedApplet && zoomFactor===1 && plasmoid.configuration.panelSize===100)
 
-    property bool forceColorizer: plasmoid.configuration.colorizeTransparentPanels
+    property bool forceColorizer: Latte.WindowSystem.compositingActive && plasmoid.configuration.colorizeTransparentPanels
 
     readonly property bool hasExpandedApplet: plasmoid.applets.some(function (item) {
         return (item.status >= PlasmaCore.Types.NeedsAttentionStatus && item.pluginName !== root.plasmoidName
@@ -1744,7 +1750,12 @@ DragDrop.DropArea {
         readonly property real themeBackgroundColorLuma: 0.2126*backColorRs + 0.7152*backColorGs + 0.0722*backColorBs
         readonly property real themeTextColorLuma: 0.2126*textColorRs + 0.7152*textColorGs + 0.0722*textColorBs
 
-        property bool isShown: active && !forceSolidPanel && plasmoid.configuration.solidBackgroundForMaximized && !root.editMode && Latte.WindowSystem.compositingActive
+        property bool isShown: active && !forceSolidPanel
+                                  //! when forceSemiTransparentPanel is enabled because of snapped or maximized etc. windows
+                                  //! then the colorizer could be enabled for low panel transparency levels (<40%)
+                               && (!forceSemiTransparentPanel || (forceSemiTransparentPanel && root.panelTransparency<40))
+                               && (plasmoid.configuration.solidBackgroundForMaximized || plasmoid.configuration.backgroundOnlyOnMaximized)
+                               && !root.editMode && Latte.WindowSystem.compositingActive
 
         property real currentBackgroundLuminas: -1000
 

shell/package/contents/configuration/TweaksConfig.qml

@@ -110,6 +110,18 @@ PlasmaComponents.Page {
                 }
             }
 
+            PlasmaComponents.CheckBox {
+                id: onlyOnMaximizedChk
+                Layout.leftMargin: units.smallSpacing * 2
+                text: i18n("Hide background for not maximized windows")
+                checked: plasmoid.configuration.backgroundOnlyOnMaximized
+                tooltip: i18n("The panel background becomes transparent except if \nthere is a maximized or snapped window")
+
+                onClicked: {
+                    plasmoid.configuration.backgroundOnlyOnMaximized = checked;
+                }
+            }
+
             PlasmaComponents.CheckBox {
                 id: colorizeTransparentPanelsChk
                 Layout.leftMargin: units.smallSpacing * 2
@@ -120,25 +132,13 @@ PlasmaComponents.Page {
                 tooltip: i18n("The panel contents are colorized in order to improve contrast \nwith the underlying desktop background when the panel is transparent")
                 style: LatteCheckBoxStyle{}
 
-                enabled: solidForMaximizedChk.checked
+                enabled: solidForMaximizedChk.checked || onlyOnMaximizedChk.checked
 
                 onClicked: {
                     plasmoid.configuration.colorizeTransparentPanels = checked;
                 }
             }
 
-            PlasmaComponents.CheckBox {
-                id: onlyOnMaximizedChk
-                Layout.leftMargin: units.smallSpacing * 2
-                text: i18n("Hide background for not maximized windows")
-                checked: plasmoid.configuration.backgroundOnlyOnMaximized
-                tooltip: i18n("The panel background becomes transparent except if \nthere is a maximized or snapped window")
-
-                onClicked: {
-                    plasmoid.configuration.backgroundOnlyOnMaximized = checked;
-                }
-            }
-
             PlasmaComponents.CheckBox {
                 id: hideShadowsOnMaximizedChk
                 Layout.leftMargin: units.smallSpacing * 2