fix buffers not clearing

src/common/buffer/Buffer.ts

@@ -16,6 +16,7 @@ import { DEFAULT_CHARSET } from 'common/data/Charsets';
 import { ExtendedAttrs } from 'common/buffer/AttributeData';
 
 export const MAX_BUFFER_SIZE = 4294967295; // 2^32 - 1
+const enum BufferState { CLEARING = 'clearing' }
 
 /**
  * This class represents a terminal buffer (an internal state of the terminal), where the
@@ -43,6 +44,7 @@ export class Buffer implements IBuffer {
   private _whitespaceCell: ICellData = CellData.fromCharData([0, WHITESPACE_CELL_CHAR, WHITESPACE_CELL_WIDTH, WHITESPACE_CELL_CODE]);
   private _cols: number;
   private _rows: number;
+  private _state: string | undefined;
 
   constructor(
     private _hasScrollback: boolean,
@@ -584,6 +586,15 @@ export class Buffer implements IBuffer {
     return x >= this._cols ? this._cols - 1 : x < 0 ? 0 : x;
   }
 
+  public clearMarkers(): void {
+    this._state = BufferState.CLEARING;
+    for (const marker of this.markers) {
+      marker.dispose();
+    }
+    this.markers = [];
+    this._state = undefined;
+  }
+
   public addMarker(y: number): Marker {
     const marker = new Marker(y);
     this.markers.push(marker);
@@ -615,7 +626,9 @@ export class Buffer implements IBuffer {
   }
 
   private _removeMarker(marker: Marker): void {
-    this.markers.splice(this.markers.indexOf(marker), 1);
+    if (this._state !== BufferState.CLEARING) {
+      this.markers.splice(this.markers.indexOf(marker), 1);
+    }
   }
 
   public iterator(trimRight: boolean, startIndex?: number, endIndex?: number, startOverscan?: number, endOverscan?: number): IBufferStringIterator {