fixes #78228

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

@@ -549,11 +549,11 @@ class LeafNode implements ISplitView, IDisposable {
 		}
 	}
 
-	setVisible(visible: boolean): void {
+	setVisible(visible: boolean, cachedVisibleSize?: number): void {
 		if (visible) {
 			this._cachedVisibleSize = undefined;
 		} else {
-			this._cachedVisibleSize = this._size;
+			this._cachedVisibleSize = typeof cachedVisibleSize === 'number' ? cachedVisibleSize : this._size;
 		}
 
 		if (this.view.setVisible) {

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

@@ -49,7 +49,7 @@ export interface IView {
 	readonly priority?: LayoutPriority;
 	readonly snap?: boolean;
 	layout(size: number, orientation: Orientation): void;
-	setVisible?(visible: boolean): void;
+	setVisible?(visible: boolean, cachedVisibleSize?: number): void;
 }
 
 interface ISashEvent {
@@ -79,7 +79,7 @@ abstract class ViewItem {
 		return typeof this._cachedVisibleSize === 'undefined';
 	}
 
-	set visible(visible: boolean) {
+	setVisible(visible: boolean, size?: number): void {
 		if (visible === this.visible) {
 			return;
 		}
@@ -88,14 +88,14 @@ abstract class ViewItem {
 			this.size = clamp(this._cachedVisibleSize!, this.viewMinimumSize, this.viewMaximumSize);
 			this._cachedVisibleSize = undefined;
 		} else {
-			this._cachedVisibleSize = this.size;
+			this._cachedVisibleSize = typeof size === 'number' ? size : this.size;
 			this.size = 0;
 		}
 
 		dom.toggleClass(this.container, 'visible', visible);
 
 		if (this.view.setVisible) {
-			this.view.setVisible(visible);
+			this.view.setVisible(visible, this._cachedVisibleSize);
 		}
 	}
 
@@ -161,6 +161,7 @@ interface ISashItem {
 interface ISashDragSnapState {
 	readonly index: number;
 	readonly limitDelta: number;
+	readonly size: number;
 }
 
 interface ISashDragState {
@@ -453,7 +454,7 @@ export class SplitView extends Disposable {
 		}
 
 		const viewItem = this.viewItems[index];
-		viewItem.visible = visible;
+		viewItem.setVisible(visible);
 
 		this.distributeEmptySpace(index);
 		this.layoutViews();
@@ -552,7 +553,8 @@ export class SplitView extends Disposable {
 
 					snapBefore = {
 						index: snapBeforeIndex,
-						limitDelta: viewItem.visible ? minDelta - halfSize : minDelta + halfSize
+						limitDelta: viewItem.visible ? minDelta - halfSize : minDelta + halfSize,
+						size: viewItem.size
 					};
 				}
 
@@ -562,7 +564,8 @@ export class SplitView extends Disposable {
 
 					snapAfter = {
 						index: snapAfterIndex,
-						limitDelta: viewItem.visible ? maxDelta + halfSize : maxDelta - halfSize
+						limitDelta: viewItem.visible ? maxDelta + halfSize : maxDelta - halfSize,
+						size: viewItem.size
 					};
 				}
 			}
@@ -740,14 +743,14 @@ export class SplitView extends Disposable {
 			const snapView = this.viewItems[snapBefore.index];
 			const visible = delta >= snapBefore.limitDelta;
 			snapped = visible !== snapView.visible;
-			snapView.visible = visible;
+			snapView.setVisible(visible, snapBefore.size);
 		}
 
 		if (!snapped && snapAfter) {
 			const snapView = this.viewItems[snapAfter.index];
 			const visible = delta < snapAfter.limitDelta;
 			snapped = visible !== snapView.visible;
-			snapView.visible = visible;
+			snapView.setVisible(visible, snapAfter.size);
 		}
 
 		if (snapped) {