After using the locator(1) to acquire x y ordinates and attempting to save graph as a metafile, the following error is produced: "first argument must be a string (of length 1) or native symbol reference."
There is no error when saving as a bitmap.
I can reproduce this, but so far haven't been able to track it down. The error happens when R tries to replay the display list on the metafile device. Presumably the locator() call has damaged something, but I haven't been able to track down what yet.
This isn't Windows specific. The following operations repeat it in OSX:
locator() # click once then stop
x <- recordPlot()
It looks as though locator() adds something to the displaylist that isn't in the appropriate format, and replaying it gives the error. There's a FIXME message in C_locator, but I don't think that's the problem.
identify() has the same problem as locator().
I think I have this now. The displaylist contained .External2(x,y,...) instead of .External2(C_locator, x,y, ...). It should be easy to fix.
Fixed in R-devel and R-patched