Don't move the Labels outside a PictureBox

Question

I am creating an application in which I can move the Labels that are on a PictureBox.
The problem is that I want these to only Labels move

Answer 1

The PictureBox control is not a container, you can't directly put another control inside it, as you would do with a Panel, a GroupBox or other controls that implement IContainerControl.
You could parent the Label (in this case), setting the Label Parent to a PictureBox handle. The Label.Bounds will then reflect the parent Bounds.
However it's not necessary: you can just calculate the position of the Label in relation to the control that contains both (Label(s) and PictureBox):

You can restrict the movements of other Label controls subscribing to the MovableLabel_MouseDown/MouseUp/MouseMove events.

An example:

bool ThisLabelCanMove;
Point LabelMousePosition = Point.Empty;

private void MovableLabel_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        LabelMousePosition = e.Location;
        ThisLabelCanMove = true;
    }
}

private void MovableLabel_MouseUp(object sender, MouseEventArgs e)
{
    ThisLabelCanMove = false;
}

private void MovableLabel_MouseMove(object sender, MouseEventArgs e)
{
    if (ThisLabelCanMove)
    {
        Label label = sender as Label;

        Point LabelNewLocation = new Point(label.Left + (e.Location.X - LabelMousePosition.X),
                                           label.Top + (e.Location.Y - LabelMousePosition.Y));
        LabelNewLocation.X = (LabelNewLocation.X < pictureBox1.Left) ? pictureBox1.Left : LabelNewLocation.X;
        LabelNewLocation.Y = (LabelNewLocation.Y < pictureBox1.Top) ? pictureBox1.Top : LabelNewLocation.Y;
        LabelNewLocation.X = (LabelNewLocation.X + label.Width > pictureBox1.Right) ? label.Left : LabelNewLocation.X;
        LabelNewLocation.Y = (LabelNewLocation.Y + label.Height > pictureBox1.Bottom) ? label.Top : LabelNewLocation.Y;
        label.Location = LabelNewLocation;
    }
}