Settings: Issue warning if theme is reinstalled unnecessarily

core/src/main/java/com/github/weisj/darklaf/LafManager.java

@@ -350,7 +350,12 @@ public final class LafManager {
      * @return the currently installed theme.
      */
     public static Theme getInstalledTheme() {
-        return installedTheme != null ? installedTheme : getTheme();
+        Theme installed = getInstalledThemeInternal();
+        return installed != null ? installed : getTheme();
+    }
+
+    private static Theme getInstalledThemeInternal() {
+        return installedTheme;
     }
 
     static void setInstalledTheme(final Theme theme) {
@@ -439,6 +444,13 @@ public final class LafManager {
      */
     public static void install() {
         Theme theme = getTheme();
+        Theme installed = getInstalledThemeInternal();
+        if (isInstalled() && installed != null && installed.appearsEqualTo(theme)) {
+            LOGGER.warning("Theme " + theme
+                    + " is already installed. Additional installs are unnecessary and should be avoided."
+                    + " The theme will be installed regardless to ensure all properties have the correct value."
+                    + " If this operation was intentional consider creating a custom theme.");
+        }
         installer.install(theme);
         setInstalledTheme(theme);
     }

core/src/main/java/com/github/weisj/darklaf/settings/ThemeSettings.java

@@ -483,7 +483,7 @@ public class ThemeSettings implements ThemePreferenceListener {
 
     protected void applyTheme(final Theme theme) {
         if (theme == null) return;
-        if (LafManager.isInstalled() && LafManager.getTheme().appearsEqualTo(theme)) return;
+        if (LafManager.isInstalled() && LafManager.getInstalledTheme().appearsEqualTo(theme)) return;
         UIThread.runOnUIThread(() -> {
             LafManager.installTheme(theme);
             refresh();