fixes #55313

src/vs/base/browser/ui/grid/grid.ts

@@ -8,7 +8,7 @@
 import 'vs/css!./gridview';
 import { Orientation } from 'vs/base/browser/ui/sash/sash';
 import { IDisposable, dispose } from 'vs/base/common/lifecycle';
-import { tail2 as tail } from 'vs/base/common/arrays';
+import { tail2 as tail, equals } from 'vs/base/common/arrays';
 import { orthogonal, IView, GridView, Sizing as GridViewSizing, Box, IGridViewStyles } from './gridview';
 import { Event } from 'vs/base/common/event';
 
@@ -256,15 +256,27 @@ export class Grid<T extends IView> implements IDisposable {
 			throw new Error('Can\'t remove last view');
 		}
 
-		if (!this.views.has(view)) {
-			throw new Error('View not found');
-		}
-
 		const location = this.getViewLocation(view);
 		this.gridview.removeView(location, sizing === Sizing.Distribute ? GridViewSizing.Distribute : undefined);
 		this.views.delete(view);
 	}
 
+	moveView(view: T, sizing: number | Sizing, referenceView: T, direction: Direction): void {
+		const sourceLocation = this.getViewLocation(view);
+		const [sourceParentLocation, from] = tail(sourceLocation);
+
+		const referenceLocation = this.getViewLocation(referenceView);
+		const targetLocation = getRelativeLocation(this.gridview.orientation, referenceLocation, direction);
+		const [targetParentLocation, to] = tail(targetLocation);
+
+		if (equals(sourceParentLocation, targetParentLocation)) {
+			this.gridview.moveView(sourceParentLocation, from, to);
+		} else {
+			this.removeView(view, typeof sizing === 'number' ? undefined : sizing);
+			this.addView(view, sizing, referenceView, direction);
+		}
+	}
+
 	swapViews(from: T, to: T): void {
 		const fromLocation = this.getViewLocation(from);
 		const toLocation = this.getViewLocation(to);

src/vs/base/browser/ui/grid/gridview.ts

@@ -181,9 +181,14 @@ class BranchNode implements ISplitView, IDisposable {
 			throw new Error('Invalid index');
 		}
 
-		const first = index === 0;
-		const last = index === this.splitview.length;
 		this.splitview.addView(node, size, index);
+		this._addChild(node, index);
+		this.onDidChildrenChange();
+	}
+
+	private _addChild(node: Node, index: number): void {
+		const first = index === 0;
+		const last = index === this.children.length;
 		this.children.splice(index, 0, node);
 		node.orthogonalStartSash = this.splitview.sashes[index - 1];
 		node.orthogonalEndSash = this.splitview.sashes[index];
@@ -195,8 +200,6 @@ class BranchNode implements ISplitView, IDisposable {
 		if (!last) {
 			this.children[index + 1].orthogonalStartSash = this.splitview.sashes[index];
 		}
-
-		this.onDidChildrenChange();
 	}
 
 	removeChild(index: number, sizing?: Sizing): void {
@@ -204,10 +207,15 @@ class BranchNode implements ISplitView, IDisposable {
 			throw new Error('Invalid index');
 		}
 
-		const first = index === 0;
-		const last = index === this.splitview.length - 1;
 		this.splitview.removeView(index, sizing);
-		this.children.splice(index, 1);
+		this._removeChild(index);
+		this.onDidChildrenChange();
+	}
+
+	private _removeChild(index: number): Node {
+		const first = index === 0;
+		const last = index === this.children.length - 1;
+		const [child] = this.children.splice(index, 1);
 
 		if (!first) {
 			this.children[index - 1].orthogonalEndSash = this.splitview.sashes[index - 1];
@@ -217,7 +225,30 @@ class BranchNode implements ISplitView, IDisposable {
 			this.children[index].orthogonalStartSash = this.splitview.sashes[Math.max(index - 1, 0)];
 		}
 
-		this.onDidChildrenChange();
+		return child;
+	}
+
+	moveChild(from: number, to: number): void {
+		if (from === to) {
+			return;
+		}
+
+		if (from < 0 || from >= this.children.length) {
+			throw new Error('Invalid from index');
+		}
+
+		if (to < 0 || to > this.children.length) {
+			throw new Error('Invalid to index');
+		}
+
+		if (from < to) {
+			to--;
+		}
+
+		this.splitview.moveView(from, to);
+
+		const child = this._removeChild(from);
+		this._addChild(child, to);
 	}
 
 	swapChildren(from: number, to: number): void {
@@ -651,6 +682,16 @@ export class GridView implements IDisposable {
 		return node.view;
 	}
 
+	moveView(parentLocation: number[], from: number, to: number): void {
+		const [, parent] = this.getNode(parentLocation);
+
+		if (!(parent instanceof BranchNode)) {
+			throw new Error('Invalid location');
+		}
+
+		parent.moveChild(from, to);
+	}
+
 	swapViews(from: number[], to: number[]): void {
 		const [fromRest, fromIndex] = tail(from);
 		const [, fromParent] = this.getNode(fromRest);

src/vs/workbench/browser/parts/editor/editorPart.ts

@@ -661,8 +661,7 @@ export class EditorPart extends Part implements EditorGroupsServiceImpl, IEditor
 		const groupHasFocus = isAncestor(document.activeElement, sourceView.element);
 
 		// Move is a simple remove and add of the same view
-		this.gridWidget.removeView(sourceView, Sizing.Distribute);
-		this.gridWidget.addView(sourceView, Sizing.Distribute, targetView, this.toGridViewDirection(direction));
+		this.gridWidget.moveView(sourceView, Sizing.Distribute, targetView, this.toGridViewDirection(direction));
 
 		// Restore focus if we had it previously (we run this after gridWidget.removeView() is called
 		// because removing a view can mean to reparent it and thus focus would be removed otherwise)