Make sure the viewport is filled when reflowing a row change

Fixes #1926

src/Buffer.ts

@@ -233,22 +233,22 @@ export class Buffer implements IBuffer {
 
     // Iterate through rows, ignore the last one as it cannot be wrapped
     if (newCols > this._cols) {
-      this._reflowLarger(newCols);
+      this._reflowLarger(newCols, newRows);
     } else {
       this._reflowSmaller(newCols, newRows);
     }
   }
 
-  private _reflowLarger(newCols: number): void {
+  private _reflowLarger(newCols: number, newRows: number): void {
     const toRemove: number[] = reflowLargerGetLinesToRemove(this.lines, newCols, this.ybase + this.y);
     if (toRemove.length > 0) {
       const newLayoutResult = reflowLargerCreateNewLayout(this.lines, toRemove);
       reflowLargerApplyNewLayout(this.lines, newLayoutResult.layout);
-      this._reflowLargerAdjustViewport(newCols, newLayoutResult.countRemoved);
+      this._reflowLargerAdjustViewport(newCols, newRows, newLayoutResult.countRemoved);
     }
   }
 
-  private _reflowLargerAdjustViewport(newCols: number, countRemoved: number): void {
+  private _reflowLargerAdjustViewport(newCols: number, newRows: number, countRemoved: number): void {
     // Adjust viewport based on number of items removed
     let viewportAdjustments = countRemoved;
     while (viewportAdjustments-- > 0) {
@@ -256,7 +256,7 @@ export class Buffer implements IBuffer {
         if (this.y > 0) {
           this.y--;
         }
-        if (this.lines.length < this._rows) {
+        if (this.lines.length < newRows) {
           // Add an extra row at the bottom of the viewport
           this.lines.push(new BufferLine(newCols, FILL_CHAR_DATA));
         }