Minimum size for new split terminals (#59140)

Fixes #45678

src/vs/workbench/parts/terminal/browser/terminalTab.ts

@@ -11,6 +11,7 @@ import { SplitView, Orientation, IView, Sizing } from 'vs/base/browser/ui/splitv
 import { IPartService, Position } from 'vs/workbench/services/part/common/partService';
 
 const SPLIT_PANE_MIN_SIZE = 120;
+const TERMINAL_MIN_USEFUL_SIZE = 250;
 
 class SplitPaneContainer {
 	private _height: number;
@@ -361,6 +362,10 @@ export class TerminalTab extends Disposable implements ITerminalTab {
 		configHelper: ITerminalConfigHelper,
 		shellLaunchConfig: IShellLaunchConfig
 	): ITerminalInstance {
+		const newTerminalSize = ((this._panelPosition === Position.BOTTOM ? this._container.clientWidth : this._container.clientHeight) / (this._terminalInstances.length + 1));
+		if (newTerminalSize < TERMINAL_MIN_USEFUL_SIZE) {
+			return undefined;
+		}
 		const instance = this._terminalService.createInstance(
 			terminalFocusContextKey,
 			configHelper,

src/vs/workbench/parts/terminal/common/terminalService.ts

@@ -83,6 +83,7 @@ export abstract class TerminalService implements ITerminalService {
 	}
 
 	protected abstract _showTerminalCloseConfirmation(): TPromise<boolean>;
+	protected abstract _showNotEnoughSpaceToast(): void;
 	public abstract createTerminal(shell?: IShellLaunchConfig, wasNewTerminalAction?: boolean): ITerminalInstance;
 	public abstract createTerminalRenderer(name: string): ITerminalInstance;
 	public abstract createInstance(terminalFocusContextKey: IContextKey<boolean>, configHelper: ITerminalConfigHelper, container: HTMLElement, shellLaunchConfig: IShellLaunchConfig, doCreateProcess: boolean): ITerminalInstance;
@@ -263,10 +264,14 @@ export abstract class TerminalService implements ITerminalService {
 		}
 
 		const instance = tab.split(this._terminalFocusContextKey, this.configHelper, shellLaunchConfig);
-		this._initInstanceListeners(instance);
-		this._onInstancesChanged.fire();
+		if (instance) {
+			this._initInstanceListeners(instance);
+			this._onInstancesChanged.fire();
 
-		this._terminalTabs.forEach((t, i) => t.setVisible(i === this._activeTabIndex));
+			this._terminalTabs.forEach((t, i) => t.setVisible(i === this._activeTabIndex));
+		} else {
+			this._showNotEnoughSpaceToast();
+		}
 	}
 
 	protected _initInstanceListeners(instance: ITerminalInstance): void {

src/vs/workbench/parts/terminal/electron-browser/terminalService.ts

@@ -56,7 +56,6 @@ export class TerminalService extends AbstractTerminalService implements ITermina
 
 		this._terminalTabs = [];
 		this._configHelper = this._instantiationService.createInstance(TerminalConfigHelper);
-
 		ipc.on('vscode:openFiles', (_event: any, request: IOpenFileRequest) => {
 			// if the request to open files is coming in from the integrated terminal (identified though
 			// the termProgram variable) and we are instructed to wait for editors close, wait for the
@@ -287,6 +286,10 @@ export class TerminalService extends AbstractTerminalService implements ITermina
 		}).then(res => !res.confirmed);
 	}
 
+	protected _showNotEnoughSpaceToast(): void {
+		this._notificationService.warn(nls.localize('terminal.minWidth', "Not enough space to split terminal."));
+	}
+
 	public setContainers(panelContainer: HTMLElement, terminalContainer: HTMLElement): void {
 		this._configHelper.panelContainer = panelContainer;
 		this._terminalContainer = terminalContainer;