Peter Hutterer, the author of the Multi-Pointer X (MPX) patches, wanted a new X extension to control MPX. So he wrote one, with the help of XCB’s protocol description language. Apparently it really is as easy as we thought it should be, because he didn’t need to ask us for help, and in his blog, he wrote: “XCB is great! Didn’t really know anything about it till yesterday but I managed to write the client-side for the MPX extension in hardly any time at all. All you have to do is write an XML file and recompile. Whoopee. Three cheers to the XCB guys.” And we didn’t even pay him to say that.