Don't show PopupMenu for inactive window on macOS.

On macOS context menu (right click) doesn't activate the window that was clicked.
- You can't  activate it yourself if some other application is active.
- It's hard to make menu work while window still is inactive (like macOS menus).
Because when you left-click anything after right click Qt makes the window
something-like-focused (it shows on top and receives input), but not really
(it still displays as inactive, cursor not blinking and all). Looks like Qt bug.

Telegram/SourceFiles/ui/widgets/popup_menu.cpp

@@ -423,6 +423,12 @@ void PopupMenu::popup(const QPoint &p) {
 }
 
 void PopupMenu::showMenu(const QPoint &p, PopupMenu *parent, TriggeredSource source) {
+	if (cPlatform() == dbipMac || cPlatform() == dbipMacOld) {
+		if (!parent && !static_cast<QApplication*>(QApplication::instance())->activeWindow()) {
+			crl::on_main(this, [=] { show(); hideFast(); });
+			return;
+		}
+	}
 	_parent = parent;
 
 	auto origin = PanelAnimation::Origin::TopLeft;