Set windows translucent without resetting the opaque region

.vscode/settings.json

@@ -59,5 +59,9 @@
         "--P",
         "#extension GL_ARB_shading_language_include : enable"
     ],
-    "task.allowAutomaticTasks": "on"
+    // ==============================================================
+    // other
+    // ==============================================================
+    "task.allowAutomaticTasks": "on",
+    "qt-ui.customWidgetsDesignerExePath": "/usr/bin/designer-qt6"
 }

src/Effect.cpp

@@ -146,7 +146,8 @@ void ShapeCorners::Effect::prePaintWindow(KWin::EffectWindow *kwindow, KWin::Win
         data.paint += reg;
 
         // Mark the window as having translucent regions.
-        data.setTranslucent();
+        data.mask |= Effect::PAINT_WINDOW_TRANSLUCENT;
+        data.mask &= ~Effect::PAINT_WINDOW_OPAQUE;
     }
 
     // Call the base implementation.

src/Effect.h

@@ -20,8 +20,8 @@
 #pragma once
 
 #include <QObject>
-#include "Shader.h"
 #include <chrono>
+#include "Shader.h"
 #if QT_VERSION_MAJOR >= 6
 #include <effect/offscreeneffect.h>
 #else

src/kcm/KCM.cpp

@@ -7,7 +7,6 @@ ShapeCorners::KCM::KCM(QObject *parent, const KPluginMetaData &args) : KCModule(
 {
     // Set up the UI for Qt 6
     ui->setupUi(KCModule::widget());
-    ui->widget->setFixedSize(800, 672);
     ui->currentWindowList->horizontalHeader()->setSectionResizeMode(QHeaderView::Stretch);
     addConfig(&config, KCModule::widget());
 

src/kcm/KCM.h

@@ -1,14 +1,16 @@
 #pragma once
 
-#include <kcmodule.h>
 #include <KLocalizedString>
+#include <kcmodule.h>
 #include "Config.h"
 
-namespace Ui {
+namespace Ui
+{
     class Form;
 }
 
-namespace ShapeCorners {
+namespace ShapeCorners
+{
 
     /**
      * @class KCM
@@ -19,8 +21,9 @@ namespace ShapeCorners {
      * It manages loading, saving, and resetting settings, as well as
      * updating the UI in response to user actions.
      */
-    class KCM final : public KCModule {
-    Q_OBJECT
+    class KCM final : public KCModule
+    {
+        Q_OBJECT
 
     public:
 #if (QT_VERSION_MAJOR >= 6)
@@ -36,7 +39,7 @@ namespace ShapeCorners {
          * @param parent The parent widget.
          * @param args Additional arguments.
          */
-        explicit KCM(QWidget* parent = nullptr, const QVariantList& args = QVariantList());
+        explicit KCM(QWidget *parent = nullptr, const QVariantList &args = QVariantList());
 #endif
 
     private Q_SLOTS:
@@ -92,7 +95,7 @@ namespace ShapeCorners {
          * @brief Returns the palette used by the widget.
          * @return Reference to the widget's palette.
          */
-        const QPalette& palette() { return widget()->palette(); };
+        const QPalette &palette() { return widget()->palette(); };
 #endif
     };
-}
+} // namespace ShapeCorners

src/kcm/KCM.ui

@@ -10,12 +10,6 @@
     <height>919</height>
    </rect>
   </property>
-  <property name="maximumSize">
-   <size>
-    <width>16777215</width>
-    <height>919</height>
-   </size>
-  </property>
   <property name="windowTitle">
    <string>Rounded Corners (formerly ShapeCorners)</string>
   </property>
@@ -77,7 +71,7 @@
    <item>
     <widget class="QTabWidget" name="tabWidget">
      <property name="currentIndex">
-      <number>2</number>
+      <number>0</number>
      </property>
      <widget class="QWidget" name="roundnessTab">
       <attribute name="title">
@@ -679,6 +673,12 @@
          <property name="orientation">
           <enum>Qt::Orientation::Vertical</enum>
          </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>0</width>
+           <height>0</height>
+          </size>
+         </property>
         </spacer>
        </item>
        <item>