Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!bloom-beacon!BBN.COM!aparisi From: aparisi@BBN.COM (Corporal Jones) Newsgroups: comp.windows.x Subject: Re: help (with a popup prompt design) Message-ID: <8908180033.AA00450@expo.lcs.mit.edu> Date: 17 Aug 89 19:13:17 GMT Sender: daemon@bloom-beacon.MIT.EDU Organization: The Internet Lines: 21 Actually, there may be a very good reason to nest an event loop. Say you need to implement a command-driven style of interaction within a toolkit application. I know we are trying to avoid this at all costs in the Brave New World of the future, but there are some large, monolithic, command-driven applications out there that people are converting to X. Often a first step in the conversion is to provide GUI front ends to a subset of the functionality, and provide a command-driven escape hatch (for example, a DECWindows Command widget) for the non-converted functionality. In this scenario, the application will want the main thread to be blocked on a command read until a command is actually entered. The way to do the block is to nest an event loop (NOT XtMainLoop, naturally-- as you said, how will it return?) in the procedure that does the read from the command widget. The event loop would terminate when a command is entered. (It probably detects this using a semaphore that is set by the command widget's commandEntered callback). Tony Parisi BBN Software Products Cambridge, MA