Opening multiple documents with Process.Start()

Question

I am trying to write a program that will open multiple documents with a single click and specify size and location for each individual document window. I was having decent success with a rudimentary program to test the opening and positioning operations until I tried to open a second Word or Excel document.

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace ConsoleApplication1
{
    class Program
    {
        [DllImport("user32.dll", SetLastError = true)]
        internal static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

        static void Main(string[] args)
        {
            Process resize = new Process();

            resize.StartInfo.FileName = "C:\\Users\\Pete\\Desktop\\TEST1.txt";
            resize.Start();
            resize.WaitForInputIdle();
            MoveWindow(resize.MainWindowHandle, 10, 10, 500, 500, true);

            resize.StartInfo.FileName = "C:\\Users\\Pete\\Desktop\\MSWTEST1.docx";
            resize.Start();
            resize.WaitForInputIdle();
            MoveWindow(resize.MainWindowHandle, 20, 20, 500, 500, true);

            resize.StartInfo.FileName = "C:\\Users\\Pete\\Desktop\\MSXTEST1.xlsx";
            resize.Start();
            resize.WaitForInputIdle();
            MoveWindow(resize.MainWindowHandle, 30, 30, 500, 500, true);

            resize.StartInfo.FileName = "C:\\Users\\Pete\\Desktop\\TEST2.txt";
            resize.Start();
            resize.WaitForInputIdle();
            MoveWindow(resize.MainWindowHandle, 40, 40, 500, 500, true);

            resize.StartInfo.FileName = "C:\\Users\\Pete\\Desktop\\MSWTEST2.docx";
            resize.Start();
            resize.WaitForInputIdle();
            MoveWindow(resize.MainWindowHandle, 50, 50, 500, 500, true);

            resize.StartInfo.FileName = "C:\\Users\\Pete\\Desktop\\MSXTEST2.xlsx";
            resize.Start();
            resize.WaitForInputIdle();
            MoveWindow(resize.MainWindowHandle, 60, 60, 500, 500, true);
         }
    }
}

The program tries to open two .txt files using Notepad, two .docx files using MSWord, and two .xlsx files using MSExcel. No matter what order I open the documents in the program throws an InvalidOperationException on the WaitForInputIdle line immediately after opening a second Word or Excel file. Any help fixing this error would be greatly appreciated.

Does the same issue arise if you don't reuse resize, i.e., have a different Process for each? — Austin Salonen
Why would you Start() multiple documents in the SAME process (resize)? — paparazzo
@Austin - Yes the same issue arises whether I use 1 process or 6 processes. — Pete Hogrefe
OR you could do it via static: Process proc = Process.Start(Execut, args);. This way you know you will always have a new window. Edit: Didn't test it with office files, only chrome. — StinkyCat

Peter Ritchie Peter Ritchie · Accepted Answer · 2013-02-13T17:34:44

When you try to open a Word or Excel document the application (depending on version) being executed simply looks for the same application already running, asks it to open a new "window" and shuts down. This means the application you're actually running never really gets a message pump--which leads to WaitForInputIdle thowing an InvalidOperationException (as documented)

I suggest you simply try to catch and ignore the exception--I'm not sure of any way to tell if Word/Excel successfully opened the document via Process.Start Update: conceptually, If you do get the exception that means Word/Excel found another running instance and switched to it--so, presumably that's some degree of "success".

Opening multiple documents with Process.Start()

3 Answers