define panel codicons

src/vs/workbench/browser/parts/panel/media/panelpart.css

@@ -170,14 +170,14 @@
 
 /* Rotate icons when panel is on right */
 .monaco-workbench .part.panel.right .title-actions .codicon-split-horizontal,
-.monaco-workbench .part.panel.right .title-actions .codicon-chevron-up,
-.monaco-workbench .part.panel.right .title-actions .codicon-chevron-down {
+.monaco-workbench .part.panel.right .title-actions .codicon-panel-maximize,
+.monaco-workbench .part.panel.right .title-actions .codicon-panel-restore {
 	transform: rotate(-90deg);
 }
 
 /* Rotate icons when panel is on left */
 .monaco-workbench .part.panel.left .title-actions .codicon-split-horizontal,
-.monaco-workbench .part.panel.left .title-actions .codicon-chevron-up,
-.monaco-workbench .part.panel.left .title-actions .codicon-chevron-down {
+.monaco-workbench .part.panel.left .title-actions .codicon-panel-maximize,
+.monaco-workbench .part.panel.left .title-actions .codicon-panel-restore {
 	transform: rotate(90deg);
 }

src/vs/workbench/browser/parts/panel/panelActions.ts

@@ -18,7 +18,11 @@ import { IActivity } from 'vs/workbench/common/activity';
 import { IEditorGroupsService } from 'vs/workbench/services/editor/common/editorGroupsService';
 import { ActivePanelContext, PanelPositionContext } from 'vs/workbench/common/panel';
 import { ContextKeyExpression } from 'vs/platform/contextkey/common/contextkey';
-import { Codicon } from 'vs/base/common/codicons';
+import { Codicon, registerIcon } from 'vs/base/common/codicons';
+
+const maximizeIcon = registerIcon('panel-maximize', Codicon.chevronUp);
+const restoreIcon = registerIcon('panel-restore', Codicon.chevronDown);
+const closeIcon = registerIcon('panel-close', Codicon.close);
 
 export class ClosePanelAction extends Action {
 
@@ -30,7 +34,7 @@ export class ClosePanelAction extends Action {
 		name: string,
 		@IWorkbenchLayoutService private readonly layoutService: IWorkbenchLayoutService
 	) {
-		super(id, name, Codicon.close.classNames);
+		super(id, name, closeIcon.classNames);
 	}
 
 	async run(): Promise<void> {
@@ -102,11 +106,11 @@ export class ToggleMaximizedPanelAction extends Action {
 		@IWorkbenchLayoutService private readonly layoutService: IWorkbenchLayoutService,
 		@IEditorGroupsService editorGroupsService: IEditorGroupsService
 	) {
-		super(id, label, layoutService.isPanelMaximized() ? 'codicon-chevron-down' : 'codicon-chevron-up');
+		super(id, label, layoutService.isPanelMaximized() ? restoreIcon.classNames : maximizeIcon.classNames);
 
 		this.toDispose.add(editorGroupsService.onDidLayout(() => {
 			const maximized = this.layoutService.isPanelMaximized();
-			this.class = maximized ? 'codicon-chevron-down' : 'codicon-chevron-up';
+			this.class = maximized ? restoreIcon.classNames : maximizeIcon.classNames;
 			this.label = maximized ? ToggleMaximizedPanelAction.RESTORE_LABEL : ToggleMaximizedPanelAction.MAXIMIZE_LABEL;
 		}));
 	}