That is not "programing code" , pdf and word are complex formats and MC is showing the content as it is.. in its binary format.
MC do not have support for viewing complex format like pdf,word. That would be project by it self that are larger then MC.
And buying in ready code for showing pdf,word are not cheap and since MC is free the budget is limited.
But your browser should be able to view PDF. so just press return/dbl click on the pdf and it should be opened by your browser. and MS have Word viewers you can install for free to view word docs.