during buffer clear, don't dispose of markers on first line

src/browser/Terminal.ts

@@ -1301,7 +1301,7 @@ export class Terminal extends CoreTerminal implements ITerminal {
       // Don't clear if it's already clear
       return;
     }
-    this.buffer.clearMarkers();
+    this.buffer.clearAllMarkers(0);
     this.buffer.lines.set(0, this.buffer.lines.get(this.buffer.ybase + this.buffer.y)!);
     this.buffer.lines.length = 1;
     this.buffer.ydisp = 0;

src/browser/TestUtils.test.ts

@@ -257,7 +257,10 @@ export class MockBuffer implements IBuffer {
   public getWhitespaceCell(attr?: IAttributeData): ICellData {
     throw new Error('Method not implemented.');
   }
-  public clearMarkers(): void {
+  public clearMarkers(y: number): void {
+    throw new Error('Method not implemented.');
+  }
+  public clearAllMarkers(excludeY: number): void {
     throw new Error('Method not implemented.');
   }
 }

src/common/buffer/Buffer.ts

@@ -585,20 +585,32 @@ export class Buffer implements IBuffer {
     return x >= this._cols ? this._cols - 1 : x < 0 ? 0 : x;
   }
 
-  public clearMarkers(y?: number): void {
+  /**
+   * Clears markers on single line.
+   * @param y The line to clear.
+   */
+  public clearMarkers(y: number): void {
     this._isClearing = true;
-    if (y !== undefined) {
-      for (let i = 0; i < this.markers.length; i++) {
-        if (this.markers[i].line === y) {
-          this.markers[i].dispose();
-          this.markers.splice(i--, 1);
-        }
+    for (let i = 0; i < this.markers.length; i++) {
+      if (this.markers[i].line === y) {
+        this.markers[i].dispose();
+        this.markers.splice(i--, 1);
       }
-    } else {
-      for (const marker of this.markers) {
-        marker.dispose();
+    }
+    this._isClearing = false;
+  }
+
+  /**
+   * Clears markers on all lines except for those on a particular line.
+   * @param excludeY The line to exclude.
+   */
+  public clearAllMarkers(excludeY: number): void {
+    this._isClearing = true;
+    for (let i = 0; i < this.markers.length; i++) {
+      if (this.markers[i].line !== excludeY) {
+        this.markers[i].dispose();
+        this.markers.splice(i--, 1);
       }
-      this.markers = [];
     }
     this._isClearing = false;
   }

src/common/buffer/Types.d.ts

@@ -45,7 +45,8 @@ export interface IBuffer {
   getNullCell(attr?: IAttributeData): ICellData;
   getWhitespaceCell(attr?: IAttributeData): ICellData;
   addMarker(y: number): IMarker;
-  clearMarkers(y?: number): void;
+  clearMarkers(y: number): void;
+  clearAllMarkers(excludeY: number): void;
 }
 
 export interface IBufferSet extends IDisposable {