Here is a sample solution on how you might wait for the upload window to appear. Note that on my system, the locating of the Chrome windows takes about three seconds each run, so the timeout isn't 100% accurate (it might take a few seconds longer than your timeout). I am looking into a method of getting the exact Chrome window which should reduce the runtime of the script and allow it to catch the window much quicker, but for now, this works in a pinch. You will need to use a little C# (UI.Automation) to tweak this for your particular application. The Chrome window and dialog may require different conditions than those I have specified. You would use a tool like "Inspect Objects" from the Windows SDK to get these properties.