Question

Is it possible to resize a running application’s window size from within another application?
I want that when the application that I am building starts, another application (let’s say itunes)’s width be reduced to its 2/3 so that the remaining 1/3 be occupied by my application. The two application should be running altogether and accessible by the user.
Please help if possible.

Answer 1

You can use SetWindowPos to resize another process’s window.

    [DllImport("user32.dll")]
    private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, 
        int x, int y, int width, int height, uint uFlags);

    private const uint SHOWWINDOW = 0x0040;

    private void resizeItunes()
    {
        System.Diagnostics.Process[] itunesProcesses = 
            System.Diagnostics.Process.GetProcessesByName("iTunes");

        if (itunesProcesses.Length > 0)
        {
            SetWindowPos(itunesProcesses[0].MainWindowHandle, this.Handle,
                0, 0, Screen.GetWorkingArea(this).Width * 2 / 3,
                Screen.GetWorkingArea(this).Height, SHOWWINDOW);
        }
    }