For everybody who is interested for future use:
simply add a new event handler for the Paint event of each panel, for example:
panel1.Paint += new PaintEventHandler(panel1_Paint);
panel2.Paint += new PaintEventHandler(panel2_Paint);
and in each of the event handlers just call a Method which retrieves the state of all the panels like so:
void panel2_Paint(object sender, PaintEventArgs e)
{
GetPanelStates();
}
void panel1_Paint(object sender, PaintEventArgs e)
{
GetPanelStates();
}
void GetPanelStates()
{
Panel2IsInFront = panel2.Parent.Controls.GetChildIndex(panel2) == 0;
Panel1IsInFront = panel1.Parent.Controls.GetChildIndex(panel1) == 0;
}