Controlling Multiple Forms in C#

Question

This is my first question so I hope I am doing this right. I am currently using Visual Studio Express 2017 doing a C# Windows Forms App project.

I have searched through Stack Overflow and YouTube for a similar examples but could find none. In the image attached, I have 3 forms in the project. Form1 which is the main controlling form and has 2 buttons on it. Form2button for Form2 and Form3button for Form3. When I click From2button, I can keep clicking and open multiple Form2's as well open multiple Form3's without limitations. I would like to run the program that if I click on Form2button it can only load one instance of Form2 and the same with Form3button.

However if I click Form3button and Form2 is open, I want Form2 to close and only have Form3 open as well as is Form3 is open and I click on Form2button, Form3 will close and Form2 will open. All the time Form1 is active on the screen.

 

namespace MultiWindows 

{ public partial class Form1 : Form { public Form1() { InitializeComponent(); }

private void Form2button_Click(object sender, EventArgs e)     

{         

Form2 f2 = new Form2();         

f2.Show();     

}      

private void Form3Button_Click(object sender, EventArgs e)     

{         

Form3 f3 = new Form3();         

f3.Show();     

} 

} 

}