widgets - more focus related methods

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

@@ -211,6 +211,10 @@ export class Button extends Disposable {
 	focus(): void {
 		this._element.focus();
 	}
+
+	hasFocus(): boolean {
+		return this._element === document.activeElement;
+	}
 }
 
 export class ButtonGroup extends Disposable {

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

@@ -230,6 +230,14 @@ export class SimpleCheckbox extends Widget {
 		this.applyStyles();
 	}
 
+	focus(): void {
+		this.domNode.focus();
+	}
+
+	hasFocus(): boolean {
+		return this.domNode === document.activeElement;
+	}
+
 	style(styles: ISimpleCheckboxStyles): void {
 		this.styles = styles;