To capture the current window you can use the following VBA code.
Public Sub SaveCurrentWindow()
Dim window As View
Set window = ThisApplication.ActiveView
Call window.SaveAsBitmap("C:\Temp\IVWindow.png", 0, 0)
End Sub
The type of image file created depends on the file extension of the filename provided. The last two arguments are the width and height of the image in pixels. In this example I used zero for both wich indicates it should use the current window size for both the height and width. I can also do something like this (filename, 0, 3000). This indicates that the width of the image will be 3000 pixels and the height will be whatever is required to maintain the same aspect ratio as the window your using to create the image. If you specifiy full values, for example (filename, 2000, 3000) then you'll get an image that specific size.