Path: utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!littlei!omepd!davidl From: davidl@intelob.intel.com (David Levine) Newsgroups: comp.windows.x Subject: Re: Support of multiple displays Message-ID: Date: 17 Apr 89 15:59:36 GMT References: <4773@jpl-devvax.JPL.NASA.GOV> <890037@hpfcdq.HP.COM> Sender: news@omepd.UUCP Organization: BiiN Information Systems, Hillsboro, Oregon Lines: 49 In-reply-to: toml@hpfcdq.HP.COM's message of 14 Apr 89 17:22:42 GMT >> 2) Is only one window manager needed for the control of both displays? If >> so, then is it possible for a window to be dragged across the displays, or >> a window to straddle the displays? Why or why not? > >A window manager like every other X clients connects to one (or more) >displays. Windows etc.. are opened with respect to that display. Dragging >a window to another display (not that any window managers would do this) >would not be allowed since the display is different and all of the clients >resources are relative to the original display. I think we have a bit of a terminology collision here. In X-ese, a "display" is a connection between the client and the server; a "screen" is a graphics display surface. A screen always belongs to a single display; a window always belongs to a single screen. However, a display can support multiple screens. A physical CRT can have more than one "screen" associated with it; the Sun server that supports "Zaphod mode" with a color and a mono screen on the same CRT does exactly this. Theoretically, a "screen" could also cover several CRTs. The Macintosh II's native windowing system can do this, but I don't know of any X server that does it. I think the original poster in this thread was using the term "display" to mean a physical CRT. There's no theoretical reason that an X server could not be written to give the desired behavior (one "screen" mapping to several CRTs). Of course, if the CRTs had different visuals, the server would have to do some fancy footwork to make them look consistent to the client. I don't know how the Mac II does it. As long as I'm posting on terminology, I'd like to mention a terminology point that's fouled me up in the past: From the client's point of view, a "display" is a server. From the server's point of view, a "display" is a client. Some clients (those that call XOpenDisplay more than once, for whatever reason) can deal with multiple displays. If those multiple "displays" are actually multiple connections to the SAME server, the server will appear to the client to be several separate displays, and the client will appear to the server to be several separate clients. If I'm blowing smoke here, feel free to correct me. I've only been working with X for a little while... David D. Levine BBBBBBBBB IIII IIII NNN NNNN TM Senior Technical Writer BBBB BBBB iiii iiii NNNN NNNN BBBBBBBBB IIII IIII NNNNNNNNN UUCP: ...[!uunet]!tektronix!biin!davidl BBBB BBBB IIII IIII NNNN NNNN MX-Internet: BBBBBBBBB IIII IIII NNNN NNN ARPA: <@iwarp.intel.com:davidl@intelob.intel.com>