Sets focus border for focused editors

Author: hediet

src/vs/editor/browser/widget/multiDiffEditorWidget/diffEditorItemTemplate.ts

@@ -230,7 +230,8 @@ export class DiffEditorItemTemplate extends Disposable implements IPooledObject<
 		this._elements.root.style.position = 'absolute';
 
 		// For sticky scroll
-		const delta = Math.max(0, Math.min(verticalRange.length - this._headerHeight, viewPort.start - verticalRange.start));
+		const maxDelta = verticalRange.length - this._headerHeight;
+		const delta = Math.max(0, Math.min(viewPort.start - verticalRange.start, maxDelta));
 		this._elements.header.style.transform = `translateY(${delta}px)`;
 
 		globalTransaction(tx => {
@@ -242,6 +243,7 @@ export class DiffEditorItemTemplate extends Disposable implements IPooledObject<
 		this.editor.getOriginalEditor().setScrollTop(editorScroll);
 
 		this._elements.header.classList.toggle('shadow', delta > 0 || editorScroll > 0);
+		this._elements.header.classList.toggle('collapsed', delta === maxDelta);
 	}
 
 	public hide(): void {

src/vs/editor/browser/widget/multiDiffEditorWidget/style.css

@@ -7,6 +7,10 @@
 	background: var(--vscode-multiDiffEditor-background);
 	overflow-y: hidden;
 
+	.focused {
+		--vscode-multiDiffEditor-border: var(--vscode-focusBorder);
+	}
+
 	.multiDiffEntry {
 		display: flex;
 		flex-direction: column;
@@ -27,6 +31,10 @@
 			z-index: 1000;
 			background: var(--vscode-editor-background);
 
+			&:not(.collapsed) .header-content {
+				border-bottom: 1px solid var(--vscode-sideBarSectionHeader-border);
+			}
+
 			.header-content {
 				margin: 8px 8px 0px 8px;
 				padding: 8px 5px;
@@ -43,8 +51,6 @@
 				color: var(--vscode-foreground);
 				background: var(--vscode-multiDiffEditor-headerBackground);
 
-				border-bottom: 1px solid var(--vscode-sideBarSectionHeader-border);
-
 				&.shadow {
 					box-shadow: var(--vscode-scrollbar-shadow) 0px 6px 6px -6px;
 				}