introduce beforeOKAction()

platform/platform-impl/src/com/intellij/ide/customize/AbstractCustomizeWizardStep.java

@@ -35,7 +35,8 @@ public abstract class AbstractCustomizeWizardStep extends JPanel {
 
   protected abstract String getHTMLFooter();
 
-  private static Color getSelectionBackground() {
+  @NotNull
+  protected static Color getSelectionBackground() {
     return ColorUtil.mix(UIUtil.getListSelectionBackground(), UIUtil.getLabelBackground(), .75);
   }
 
@@ -75,4 +76,8 @@ public abstract class AbstractCustomizeWizardStep extends JPanel {
 
   public void beforeShown(boolean forward) {
   }
+
+  public boolean beforeOkAction() {
+    return true;
+  }
 }

platform/platform-impl/src/com/intellij/ide/customize/CustomizeIDEWizardDialog.java

@@ -141,6 +141,9 @@ public class CustomizeIDEWizardDialog extends DialogWrapper implements ActionLis
 
   @Override
   protected void doOKAction() {
+    for (AbstractCustomizeWizardStep step : mySteps) {
+      if (!step.beforeOkAction()) return;
+    }
     try {
       PluginManager.saveDisabledPlugins(PluginGroups.getInstance().getDisabledPluginIds(), false);
     }