Many apps will let you open a page into a different app to work on it, but the choices are very limited. Is there a way to expand this selection? For instance, if I have googled up a document in PDF Format and select "open in", the only app choices offered are Chrome and Safari. Or, more likely, I get an e-mail with a PDF attachment. How do I open these in an other app, such as PDF FORMS? "Copy & paste" does not always preserve the correct format.