Simple image capture program This program is eventually going to be a screen recorder, but right now I just want it to capture screen images.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Drawing;
using System.Windows.Forms;


namespace ScreenRecorder
{
    /// &lt;summary&gt;
    /// Interaction logic for MainWindow.xaml
    /// &lt;/summary&gt;
    public partial class MainWindow : Window
    {
        public static bool recording = false;
        public static string saveAddress = @"C:\Users\UserName\Desktop\something.bmp";

        public MainWindow()
        {
            InitializeComponent();
        }

        private void onClick(object sender, RoutedEventArgs e)
        {
            System.Drawing.Image currentImage; 
            if (recording == false)
            {
                currentImage =  this.CaptureScreen();
                recording = true;
                recorderButton.Content = "Stop Recording!";
                currentImage.Save(saveAddress);
            }
            else
            {
                recording = false;
                recorderButton.Content = "Start Recording!";
            }
        }

        private System.Drawing.Image CaptureScreen()
        {
            System.Drawing.Rectangle screenSize = Screen.PrimaryScreen.Bounds;
            Bitmap target = new Bitmap(screenSize.Width, screenSize.Height);
            using (Graphics g = Graphics.FromImage(target))
            {
                g.CopyFromScreen(0, 0, 0, 0, new System.Drawing.Size(screenSize.Width, screenSize.Height));
            }
            return target;
        }
    }
}
Considering there is almost no code to review, this will be purely stylistic. Remember that criticism is a sign of love.

/// &lt;summary&gt;
/// Interaction logic for MainWindow.xaml
/// &lt;/summary&gt;



The comment isn't needed, we all know what a codebehind is for. Comments should explain the why, not the what.
You should (almost) never have public fields. If they are actually needed outside of the current object's scope then you should make them properties, otherwise private.
Are they consciously static? This will mess up your program if you execute it multiple times simultaneously. A static modifier on a field is something you probably won't need very often and should be avoided unless needed.
You're hardcoding the user's path. It would be more userfriendly to let them pick this through a FolderBrowserDialog.
C#'s naming conventions dictate that methods are UpperCamelCase, not lowerCamelCase.
You've already imported System.Drawing, remove all the explicit namespace naming in your code.
currentImage is only used inside the first part of your if block so you should declare it there. Always restrict the visibility of variables to the most-restrictive scope possible. You'll notice you won't even need the temporary variable and might as well use CaptureScreen().Save(saveAddress).
if(recording == false) can be less verbosely written as if(!recording).
Don't use this unless you need it to distinguish between members of different scopes. 
Use resource files to store your buttons their text so you can easily re-use messages and add additional languages. It also allows you to centrally manage all messages.
CaptureScreen() indicates a long-running operation with perhaps events raised to return information. That's not the case here. I suggest naming it GetScreenCapture().
Some people prefer using var to - again - be less verbose.