grid: disable sash snapping on edge of grid

fixes #84315

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

@@ -121,6 +121,8 @@ interface ILayoutContext {
 	readonly orthogonalSize: number;
 	readonly absoluteOffset: number;
 	readonly absoluteOrthogonalOffset: number;
+	readonly absoluteSize: number;
+	readonly absoluteOrthogonalSize: number;
 }
 
 class BranchNode implements ISplitView<ILayoutContext>, IDisposable {
@@ -238,7 +240,7 @@ class BranchNode implements ISplitView<ILayoutContext>, IDisposable {
 		if (!childDescriptors) {
 			// Normal behavior, we have no children yet, just set up the splitview
 			this.splitview = new SplitView(this.element, { orientation, styles, proportionalLayout });
-			this.splitview.layout(size, { orthogonalSize, absoluteOffset: 0, absoluteOrthogonalOffset: 0 });
+			this.splitview.layout(size, { orthogonalSize, absoluteOffset: 0, absoluteOrthogonalOffset: 0, absoluteSize: size, absoluteOrthogonalSize: orthogonalSize });
 		} else {
 			// Reconstruction behavior, we want to reconstruct a splitview
 			const descriptor = {
@@ -303,8 +305,14 @@ class BranchNode implements ISplitView<ILayoutContext>, IDisposable {
 		this.splitview.layout(ctx.orthogonalSize, {
 			orthogonalSize: size,
 			absoluteOffset: this.absoluteOrthogonalOffset,
-			absoluteOrthogonalOffset: this.absoluteOffset
+			absoluteOrthogonalOffset: this.absoluteOffset,
+			absoluteSize: ctx.absoluteOrthogonalSize,
+			absoluteOrthogonalSize: ctx.absoluteSize
 		});
+
+		// Disable snapping on views which sit on the edges of the grid
+		this.splitview.startSnappingEnabled = this.absoluteOrthogonalOffset > 0;
+		this.splitview.endSnappingEnabled = this.absoluteOrthogonalOffset + ctx.orthogonalSize < ctx.absoluteOrthogonalSize;
 	}
 
 	setVisible(visible: boolean): void {
@@ -751,7 +759,7 @@ export class GridView implements IDisposable {
 
 		const { size, orthogonalSize } = this._root;
 		this.root = flipNode(this._root, orthogonalSize, size);
-		this.root.layout(size, 0, { orthogonalSize, absoluteOffset: 0, absoluteOrthogonalOffset: 0 });
+		this.root.layout(size, 0, { orthogonalSize, absoluteOffset: 0, absoluteOrthogonalOffset: 0, absoluteSize: size, absoluteOrthogonalSize: orthogonalSize });
 	}
 
 	get width(): number { return this.root.width; }
@@ -807,7 +815,7 @@ export class GridView implements IDisposable {
 		this.firstLayoutController.isLayoutEnabled = true;
 
 		const [size, orthogonalSize] = this.root.orientation === Orientation.HORIZONTAL ? [height, width] : [width, height];
-		this.root.layout(size, 0, { orthogonalSize, absoluteOffset: 0, absoluteOrthogonalOffset: 0 });
+		this.root.layout(size, 0, { orthogonalSize, absoluteOffset: 0, absoluteOrthogonalOffset: 0, absoluteSize: size, absoluteOrthogonalSize: orthogonalSize });
 	}
 
 	addView(view: IView, size: number | Sizing, location: number[]): void {

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

@@ -269,6 +269,10 @@ export class SplitView<TLayoutContext = undefined> extends Disposable {
 	private _startSnappingEnabled = true;
 	get startSnappingEnabled(): boolean { return this._startSnappingEnabled; }
 	set startSnappingEnabled(startSnappingEnabled: boolean) {
+		if (this._startSnappingEnabled === startSnappingEnabled) {
+			return;
+		}
+
 		this._startSnappingEnabled = startSnappingEnabled;
 		this.updateSashEnablement();
 	}
@@ -276,6 +280,10 @@ export class SplitView<TLayoutContext = undefined> extends Disposable {
 	private _endSnappingEnabled = true;
 	get endSnappingEnabled(): boolean { return this._endSnappingEnabled; }
 	set endSnappingEnabled(endSnappingEnabled: boolean) {
+		if (this._endSnappingEnabled === endSnappingEnabled) {
+			return;
+		}
+
 		this._endSnappingEnabled = endSnappingEnabled;
 		this.updateSashEnablement();
 	}