prevent multiple active stackable plugins

Author: kaeizen

plugin.php

@@ -17,15 +17,27 @@
 	exit;
 }
 
+if ( ! function_exists( 'stackable_multiple_plugins_check' ) ) {
+	// Prevent multiple Stackable plugin versions from being active simultaneously.
+	function stackable_multiple_plugins_check() {
+		if ( is_plugin_active( $GLOBALS['OTHER_STACKABLE_FILE'] ) ) {
+			deactivate_plugins( $GLOBALS['OTHER_STACKABLE_FILE'] );
+		}
+	}
+}
+
+if ( defined('STACKABLE_FILE') && STACKABLE_FILE !== __FILE__ && ! isset( $GLOBALS['OTHER_STACKABLE_FILE'] ) ) {
+	// Get relative file path of the other Stackable version.
+	preg_match( "#([^\/]*?\/plugin.php)$#", STACKABLE_FILE, $matches );
+	$GLOBALS['OTHER_STACKABLE_FILE'] = $matches[1];
+
+	register_activation_hook( __FILE__, 'stackable_multiple_plugins_check' );
+}
+
 // Freemius SDK: Auto deactivate the free version when activating the paid one.
 if ( function_exists( 'sugb_fs' ) ) {
-	 // Prevent PHP errors by checking sugb_fs return value.
-    // In the free version, sugb_fs() is a no-op function that returns null.
-    // Only proceed if sugb_fs() returns an object (i.e., the Freemius SDK is loaded).
-    if ( is_object( sugb_fs() ) ) {
-        sugb_fs()->set_basename( false, __FILE__ );
-        return;
-    }
+	sugb_fs()->set_basename( true, __FILE__ );
+	return;
 }
 
 defined( 'STACKABLE_SHOW_PRO_NOTICES' ) || define( 'STACKABLE_SHOW_PRO_NOTICES', true );
@@ -218,11 +230,6 @@ function is_frontend() {
  */
 if ( STACKABLE_BUILD !== 'free' ) {
 	require_once( plugin_dir_path( __FILE__ ) . 'freemius.php' );
-} else if ( ! function_exists( 'sugb_fs' ) ) {
-    // Provide a no-op sugb_fs() stub for compatibility when Freemius SDK is not loaded.
-    // This allows themes and plugins to safely check for Stackable's presence.
-    // The function returns null and performs no actions.
-    function sugb_fs() {};
 }
 
 /**