address open dialog delay issue

Author: brtnfld

hdfview/src/main/java/hdf/view/HDFView.java

@@ -515,9 +515,6 @@ public void widgetDisposed(DisposeEvent e)
 
         log.info("Main Window created");
 
-        // Start background class warm-up for all platforms
-        startBackgroundClassWarmup(shell);
-
         return shell;
     }
 
@@ -1104,71 +1101,24 @@ else if (id == SWT.ID_PREFERENCES) {
         log.info("macOS application menu handlers configured");
     }
 
-    /**
-     * Schedules background pre-creation of the User Options dialog on the UI thread.
-     * This eliminates the 2-3 second freeze when the user first clicks Preferences.
-     * The dialog is created in the background after startup, then cached for instant reuse.
-     *
-     * @param shell the main shell (used to access the Display and as parent for dialog)
-     */
-    private void startBackgroundClassWarmup(final Shell shell)
-    {
-        final Display display = shell.getDisplay();
-
-        // Schedule dialog creation on the UI thread after a 2-second delay
-        // This delay ensures the UI is fully initialized and startup is complete
-        display.timerExec(2000, () -> {
-            if (shell.isDisposed()) {
-                return; // Don't run if the shell was closed during the delay
-            }
-
-            try {
-                log.debug("Pre-creating User Options dialog in background...");
-
-                // Pre-create the entire dialog structure (this is what takes 2-3 seconds)
-                // The dialog will be cached and reused when the user clicks Preferences
-                PreferenceManager mgr = new PreferenceManager();
-
-                UserOptionsNode generalNode = new UserOptionsNode("general", new UserOptionsGeneralPage());
-                UserOptionsNode hdfNode     = new UserOptionsNode("hdf", new UserOptionsHDFPage());
-                UserOptionsNode modulesNode = new UserOptionsNode("modules", new UserOptionsViewModulesPage());
-
-                mgr.addToRoot(generalNode);
-                mgr.addToRoot(hdfNode);
-                mgr.addToRoot(modulesNode);
-
-                userOptionDialog = new UserOptionsDialog(shell, mgr, rootDir);
-                userOptionDialog.setPreferenceStore(props);
-                userOptionDialog.create(); // This creates all the SWT widgets (expensive!)
-
-                log.info("User Options dialog pre-created successfully - first open will be instant");
-            }
-            catch (Throwable t) {
-                // If pre-creation fails, the dialog will be created on-demand when user clicks
-                log.warn("Failed to pre-create User Options dialog (will create on-demand): {}",
-                         t.getMessage());
-                userOptionDialog = null; // Ensure we don't keep a broken reference
-            }
-        });
-
-        log.debug("Background dialog pre-creation scheduled");
-    }
-
     /**
      * Opens the User Options dialog. Extracted to a separate method for reuse
      * by both the Tools menu and the macOS Preferences menu item.
      *
+     * The dialog is cached after first creation, making subsequent opens instant.
+     * First open takes 2-3 seconds (creates all widgets), later opens are instant.
+     *
      * @param parentShell the parent shell for the dialog
      */
     private void openUserOptionsDialog(Shell parentShell)
     {
-        // Check if we have a pre-created dialog that's still valid
+        // Check if we have a cached dialog that's still valid
         boolean needsCreation = (userOptionDialog == null) ||
                                 (userOptionDialog.getShell() != null &&
                                  userOptionDialog.getShell().isDisposed());
 
         if (needsCreation) {
-            log.debug("Creating User Options dialog (first open or after disposal)...");
+            log.debug("Creating User Options dialog (first open or after disposal) - this takes ~2 seconds...");
 
             // Create the preference manager
             PreferenceManager mgr = new PreferenceManager();
@@ -1191,10 +1141,10 @@ private void openUserOptionsDialog(Shell parentShell)
             userOptionDialog.create();
         }
         else {
-            log.debug("Reusing pre-created User Options dialog (instant open)");
+            log.debug("Reusing cached User Options dialog (instant open)");
         }
 
-        // Open the dialog (instant if pre-created, or newly created if needed)
+        // Open the dialog (instant if cached, or newly created if needed)
         userOptionDialog.open();
 
         // TODO(HDFView) [2025-01]: TECHNICAL DEBT - Fix work directory change detection