Reduce flickering when switching theme on windows.

core/src/main/java/com/github/weisj/darklaf/platform/DefaultDecorationsProvider.java

@@ -37,10 +37,10 @@ public class DefaultDecorationsProvider implements DecorationsProvider {
     public CustomTitlePane createTitlePane(final JRootPane rootPane, final int decorationStyle, final Window window) {
         return new CustomTitlePane() {
             @Override
-            public void install() {}
+            public void uninstall(final boolean removeDecorations) {}
 
             @Override
-            public void uninstall() {}
+            public void install() {}
         };
     }
 

core/src/main/java/com/github/weisj/darklaf/ui/rootpane/DarkRootPaneUI.java

@@ -33,6 +33,8 @@ import javax.swing.*;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicRootPaneUI;
 
+import com.github.weisj.darklaf.DarkLaf;
+import com.github.weisj.darklaf.LafManager;
 import com.github.weisj.darklaf.platform.DecorationsHandler;
 import com.github.weisj.darklaf.platform.decorations.CustomTitlePane;
 import com.github.weisj.darklaf.util.DarkUIUtil;
@@ -122,7 +124,9 @@ public class DarkRootPaneUI extends BasicRootPaneUI implements HierarchyListener
             uninstallBorder(root);
             root.removeHierarchyListener(this);
             if (titlePane != null) {
-                titlePane.uninstall();
+                boolean removeDecorations = !(UIManager.getLookAndFeel() instanceof DarkLaf)
+                                            || !LafManager.isDecorationsEnabled();
+                titlePane.uninstall(removeDecorations);
                 setTitlePane(root, null);
             }
             uninstallLayout(root);

macos/src/main/java/com/github/weisj/darklaf/platform/macos/ui/MacOSTitlePane.java

@@ -138,7 +138,7 @@ public class MacOSTitlePane extends CustomTitlePane {
     }
 
     @Override
-    public void uninstall() {
+    public void uninstall(final boolean removeDecorations) {
         if (titleLabel != null) {
             remove(titleLabel);
             titleLabel = null;

platform-base/src/main/java/com/github/weisj/darklaf/platform/decorations/CustomTitlePane.java

@@ -32,7 +32,7 @@ public abstract class CustomTitlePane extends JComponent {
 
     protected int decorationStyle;
 
-    public abstract void uninstall();
+    public abstract void uninstall(final boolean removeDecorations);
 
     /**
      * Do not call directly.

windows/src/main/java/com/github/weisj/darklaf/platform/windows/ui/WindowsTitlePane.java

@@ -172,9 +172,10 @@ public class WindowsTitlePane extends CustomTitlePane {
         return button;
     }
 
-    public void uninstall() {
+    @Override
+    public void uninstall(final boolean removeDecorations) {
         uninstallListeners();
-        uninstallDecorations();
+        uninstallDecorations(removeDecorations);
         removeAll();
         if (menuBar != null) {
             getRootPane().setJMenuBar(menuBar);
@@ -192,9 +193,11 @@ public class WindowsTitlePane extends CustomTitlePane {
         }
     }
 
-    protected void uninstallDecorations() {
+    protected void uninstallDecorations(final boolean removeDecorations) {
         if (windowHandle != 0) {
-            JNIDecorationsWindows.uninstallDecorations(windowHandle, decorationStyle != JRootPane.NONE);
+            if (removeDecorations) {
+                JNIDecorationsWindows.uninstallDecorations(windowHandle, decorationStyle != JRootPane.NONE);
+            }
             windowHandle = 0;
         }
         rootPane.removeContainerListener(rootPaneContainerListener);
@@ -228,7 +231,7 @@ public class WindowsTitlePane extends CustomTitlePane {
     public void setDecorationsStyle(final int style) {
         super.setDecorationsStyle(style);
         if (style == JRootPane.NONE && windowHandle != 0) {
-            uninstall();
+            uninstall(true);
         } else if (windowHandle == 0) {
             install();
         }
@@ -245,7 +248,7 @@ public class WindowsTitlePane extends CustomTitlePane {
                 Color color = rootPane.getBackground();
                 JNIDecorationsWindows.setBackground(windowHandle, color.getRed(), color.getGreen(), color.getBlue());
             } else {
-                uninstall();
+                uninstall(decorationStyle != JRootPane.NONE);
                 return false;
             }
         }