try workaround for not being able to focus window on win & linux

src/vs/workbench/electron-browser/window.ts

@@ -174,7 +174,11 @@ export class ElectronWindow {
 
 	public focus(): void {
 		if (!this.win.isFocused()) {
-			this.win.focus();
+			if (platform.isWindows || platform.isLinux) {
+				this.win.show(); // Windows & Linux sometimes cannot bring the window to the front when it is in the background
+			} else {
+				this.win.focus();
+			}
 		}
 	}
 

src/vs/workbench/electron-main/window.ts

@@ -215,7 +215,11 @@ export class VSCodeWindow {
 			this._win.restore();
 		}
 
-		this._win.focus();
+		if (platform.isWindows || platform.isLinux) {
+			this._win.show(); // Windows & Linux sometimes cannot bring the window to the front when it is in the background
+		} else {
+			this._win.focus();
+		}
 	}
 
 	public get lastFocusTime(): number {