Store the form references outside the click events:
private ObjectPlacement? objectPlacement;
private ManualControl? manualControl;
public Form1()
{
InitializeComponent();
}
private void Object_Placement_btn_Click(object sender, EventArgs e)
{
if (manualControl is not null)
{
manualControl.Hide();
manualControl = null;
}
if (objectPlacement is not null)
return;
objectPlacement = new ObjectPlacement();
objectPlacement.Show();
}
private void Manual_Control_btn_Click(object sender, EventArgs e)
{
if (objectPlacement is not null)
{
objectPlacement.Hide();
objectPlacement = null;
}
if (manualControl is not null)
return;
manualControl = new ManualControl();
manualControl.Show();
}