Allow enabling/disabling window shadows

assets/qml/FramelessWindow/CustomWindow.qml

@@ -97,7 +97,8 @@ QtWindow.Window {
     //
     // Size of the shadow object
     //
-    property int shadowMargin: Cpp_IsMac ? 0 : (root.radius > 0 ? 20 : 0)
+    property int shadowMargin: (Cpp_IsMac | !Cpp_ThemeManager.shadowsEnabled) ?
+                                   0 : (root.radius > 0 ? 20 : 0)
 
     //
     // Titlebar left/right margins for custom controls

assets/qml/Panes/SetupPanes/Settings.qml

@@ -35,6 +35,7 @@ Control {
     property alias tcpPlugins: _tcpPlugins.checked
     property alias language: _langCombo.currentIndex
     property alias startSequence: _startSequence.text
+    property alias windowShadows: _windowShadows.checked
     property alias separatorSequence: _separatorSequence.text
     property alias multithreadedFrameProcessing: _multithreadedFrameProcessing.checked
 
@@ -166,6 +167,24 @@ Control {
                         Cpp_JSON_Generator.processFramesInSeparateThread = checked
                 }
             }
+
+            //
+            // Window shadows
+            //
+            Label {
+                visible: !Cpp_IsMac
+                text: qsTr("Window shadows") + ": "
+            } Switch {
+                id: _windowShadows
+                visible: !Cpp_IsMac
+                Layout.leftMargin: -app.spacing
+                Layout.alignment: Qt.AlignLeft
+                checked: Cpp_ThemeManager.shadowsEnabled
+                onCheckedChanged: {
+                    if (checked != Cpp_ThemeManager.shadowsEnabled)
+                        Cpp_ThemeManager.shadowsEnabled = checked
+                }
+            }
         }
 
         //

src/Misc/ThemeManager.cpp

@@ -41,6 +41,7 @@ Misc::ThemeManager::ThemeManager()
 {
     populateThemes();
     loadTheme(m_settings.value("themeId", 0).toInt());
+    setShadowsEnabled(m_settings.value("shadowsEnabled", true).toBool());
 }
 
 /**
@@ -60,6 +61,16 @@ int Misc::ThemeManager::themeId() const
     return m_themeId;
 }
 
+/**
+ * Returns @c true if the application should draw window shadows. This feature makes the
+ * frameless windows look good - except if the DE does not support composting (e.g. CDE
+ * or Haiku OS).
+ */
+bool Misc::ThemeManager::shadowsEnabled() const
+{
+    return m_enableShadows;
+}
+
 /**
  * Updates the theme ID to be used & saves the changes to the
  * application settings.
@@ -93,6 +104,13 @@ void Misc::ThemeManager::setTheme(const int id)
         Utilities::rebootApplication();
 }
 
+void Misc::ThemeManager::setShadowsEnabled(const bool enabled)
+{
+    m_enableShadows = enabled;
+    m_settings.setValue("shadowsEnabled", enabled);
+    Q_EMIT shadowsEnabledChanged();
+}
+
 /**
  * Parses the JSON theme definition file for the given theme ID.
  * The colors are then "extracted" from the JSON file & loaded into the

src/Misc/ThemeManager.h

@@ -193,10 +193,15 @@ class ThemeManager : public QObject
     Q_PROPERTY(StringList availableThemes
                READ availableThemes
                NOTIFY availableThemesChanged)
+    Q_PROPERTY(bool shadowsEnabled
+               READ shadowsEnabled
+               WRITE setshadowsEnabled
+               NOTIFY shadowsEnabledChanged)
     // clang-format on
 
 Q_SIGNALS:
     void themeChanged();
+    void shadowsEnabledChanged();
     void availableThemesChanged();
 
 private:
@@ -210,6 +215,7 @@ public:
     static ThemeManager &instance();
 
     int themeId() const;
+    bool shadowsEnabled() const;
 
     bool titlebarSeparator() const;
     QColor base() const;
@@ -264,6 +270,7 @@ public:
 
 public Q_SLOTS:
     void setTheme(const int id);
+    void setShadowsEnabled(const bool enabled);
 
 private Q_SLOTS:
     void populateThemes();
@@ -271,6 +278,8 @@ private Q_SLOTS:
 
 private:
     int m_themeId;
+    bool m_enableShadows;
+
     QSettings m_settings;
     bool m_titlebarSeparator;
     StringList m_availableThemes;