Some memories of the old RISC OS (Acorn): There was an implementation of OLE (similar to Windows, I think) where a desktop publishing tool would display a frame

Some memories of the old RISC OS (Acorn): There was an implementation of OLE (similar to Windows, I think) where a desktop publishing tool would display a frame containing data from another application. Double-clicking would open the other application to edit it. In later year I remember this extended to a demos of a concept called PCA where the application and its toolbars existing in-place. I feel these concepts were along the right lines (and probably they go all the way back to Xerox PARC) but it would be interesting to come up with equivalents for a non document-oriented world -- embed an image in a calendar entry, edit it, send an email containing the calendar entries etc.