Enable cbs only for left mouse button

src/components/modules/crossBlockSelection.ts

@@ -20,6 +20,10 @@ export default class CrossBlockSelection extends Module {
    * @param {MouseEvent} event - mouse down event
    */
   public watchSelection(event: MouseEvent): void {
+    if (event.button !== _.mouseButtons.LEFT) {
+      return;
+    }
+
     const {BlockManager, UI, Listeners} = this.Editor;
 
     this.firstSelectedBlock = BlockManager.getBlock(event.target as HTMLElement);

src/components/utils.ts

@@ -83,6 +83,19 @@ export default class Util {
     };
   }
 
+  /**
+   * Return mouse buttons codes
+   */
+  static get mouseButtons() {
+    return {
+      LEFT: 0,
+      WHEEL: 1,
+      RIGHT: 2,
+      BACKWARD: 3,
+      FORWARD: 4,
+    };
+  }
+
   /**
    * Returns true if passed key code is printable (a-Z, 0-9, etc) character.
    * @param {number} keyCode