Prevent clear from flashing in terminal sticky scroll (microsoft#268921)

* Allow canceling of debounce for _show

* Polish

* Still no luck with RunOnceScheduler, clear always tries to show itself before the second hide

* Just don't show sticky UI for clear command

* Pass command object in _isClearCommand

* Last Polish

Author: anthonykim1

src/vs/workbench/contrib/terminalContrib/stickyScroll/browser/terminalStickyScrollOverlay.ts

@@ -227,8 +227,8 @@ export class TerminalStickyScrollOverlay extends Disposable {
 		// scroll.
 		this._currentStickyCommand = undefined;
 
-		// No command
-		if (!command) {
+		// No command or clear command
+		if (!command || this._isClearCommand(command)) {
 			this._setVisible(false);
 			return;
 		}
@@ -521,6 +521,20 @@ export class TerminalStickyScrollOverlay extends Disposable {
 			selectionInactiveBackground: undefined
 		};
 	}
+
+	private _isClearCommand(command: ITerminalCommand | ICurrentPartialCommand): boolean {
+		if (!command.command) {
+			return false;
+		}
+		const trimmedCommand = command.command.trim().toLowerCase();
+		const clearCommands = [
+			'clear',
+			'cls',
+			'clear-host',
+		];
+
+		return clearCommands.includes(trimmedCommand);
+	}
 }
 
 function lineStartsWith(line: IBufferLine | undefined, text: string): boolean {