[KCMs] Apply by double clicking on thumbnails in Appearance KCMs

kcms/cursortheme/package/contents/ui/Delegate.qml

@@ -80,4 +80,7 @@ KCM.GridDelegate {
         view.forceActiveFocus();
         kcm.cursorThemeSettings.cursorTheme = kcm.cursorThemeFromIndex(index);
     }
+    onDoubleClicked: {
+            kcm.save();
+    }
 }

kcms/desktoptheme/package/contents/ui/main.qml

@@ -151,6 +151,9 @@ KCM.GridViewKCM {
             kcm.desktopThemeSettings.name = model.pluginName;
             view.forceActiveFocus();
         }
+        onDoubleClicked: {
+            kcm.save();
+        }
     }
 
     footer: ColumnLayout {

kcms/icons/package/contents/ui/main.qml

@@ -176,6 +176,9 @@ KCM.GridViewKCM {
             }
             view.forceActiveFocus();
         }
+        onDoubleClicked: {
+            kcm.save();
+        }
     }
 
     footer: ColumnLayout {

kcms/lookandfeel/package/contents/ui/main.qml

@@ -66,6 +66,9 @@ KCM.GridViewKCM {
             view.forceActiveFocus();
             resetCheckbox.checked = false;
         }
+        onDoubleClicked: {
+            kcm.save();
+        }
     }
 
     footer: ColumnLayout {

kcms/style/package/contents/ui/main.qml

@@ -116,6 +116,9 @@ KCM.GridViewKCM {
             kcm.model.selectedStyle = model.styleName;
             view.forceActiveFocus();
         }
+        onDoubleClicked: {
+            kcm.save();
+        }
     }
 
     footer: ColumnLayout {