Fix screen grab error (#2139)

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

src/core/controller.cpp

@@ -318,7 +318,7 @@ void Controller::startVisualCapture(const uint id,
 void Controller::startScreenGrab(const uint id, const int screenNumber)
 {
     bool ok = true;
-    auto screen = qApp->screens()[screenNumber];
+    QScreen* screen;
 
     if (screenNumber < 0) {
         QPoint globalCursorPos = QCursor::pos();
@@ -328,6 +328,8 @@ void Controller::startScreenGrab(const uint id, const int screenNumber)
         screen =
           qApp->screens()[qApp->desktop()->screenNumber(globalCursorPos)];
 #endif
+    } else {
+        screen = qApp->screens()[screenNumber];
     }
     QPixmap p(ScreenGrabber().grabScreen(screen, ok));
     if (ok) {

src/utils/screengrabber.cpp

@@ -179,9 +179,8 @@ QPixmap ScreenGrabber::grabScreen(QScreen* screen, bool& ok)
         }
     } else {
         ok = true;
-        QScreen* currentScreen = QGuiAppCurrentScreen().currentScreen();
-        return currentScreen->grabWindow(
-          geometry.x(), geometry.y(), geometry.width(), geometry.height());
+        return screen->grabWindow(
+          0, geometry.x(), geometry.y(), geometry.width(), geometry.height());
     }
     return p;
 }