I've since extended things so that the DataEngine now includes a Service object, allowing plasmoids to write data too. Instead of tracking an XWindow, this time around I'll track a Google Spreadsheet and update it through the plasmoid. Doing this makes a mounted web service like GSpreads into a pastebin with access control applied. So you can share your clipboard with anyone in your "group" or company and stop others getting at it.
The two plasmoids show two spreadsheet cells, the top one is the top coloured cell and the bottom plasmoid is the lower, purple cell. The purple cell in the spreadsheet is the sum of the three cells in the column around the peachy cell above it.
First, updating the spreadsheet through the browser is reflected in the plasmoid. Towards the end I copy and paste a number into the top plasmoid, which updates the peach cell in the spreadsheet, which in turn causes the purple cell to update and so the lower plasmoid shows this updated sum. Of course, these two plasmoids don't have to be on the same machine. For tracking sums or other formulas, the ferris_graph might be more interesting if you are more interested in the trends than the current value.
plasma-google-spread.avi from Ben Martin on Vimeo.
