Allow markers on the alt buffer

src/browser/Terminal.ts

@@ -956,11 +956,6 @@ export class Terminal extends CoreTerminal implements ITerminal {
   }
 
   public addMarker(cursorYOffset: number): IMarker | undefined {
-    // Disallow markers on the alt buffer
-    if (this.buffer !== this.buffers.normal) {
-      return;
-    }
-
     return this.buffer.addMarker(this.buffer.ybase + this.buffer.y + cursorYOffset);
   }
 

src/common/buffer/BufferSet.test.ts

@@ -71,4 +71,14 @@ describe('BufferSet', () => {
       assert.equal(bufferSet.active.y, 10);
     });
   });
+
+  describe('markers', () => {
+    it('should clear the markers when the buffer is switched', () => {
+      bufferSet.activateAltBuffer();
+      bufferSet.alt.addMarker(1);
+      assert.equal(bufferSet.alt.markers.length, 1);
+      bufferSet.activateNormalBuffer();
+      assert.equal(bufferSet.alt.markers.length, 0);
+    });
+  });
 });

src/common/buffer/BufferSet.ts

@@ -83,6 +83,7 @@ export class BufferSet extends Disposable implements IBufferSet {
     // The alt buffer should always be cleared when we switch to the normal
     // buffer. This frees up memory since the alt buffer should always be new
     // when activated.
+    this._alt.clearAllMarkers();
     this._alt.clear();
     this._activeBuffer = this._normal;
     this._onBufferActivate.fire({