When you first log in after installing the dual channel software and hardware, dual channel mode is not enabled. Before enabling it, you may want to configure the cursor movement and the window manager maximize behavior.

Configuring the Mouse for Horizontal Cursor Movement

The default cursor movement is vertical from top to bottom and vice versa. If you prefer a horizontal, left to right and right to left cursor movement, shown in Figure 3-1, you can reconfigure the cursor. To do this:

1. Choose Desktop > Open Unix Shell from the Toolchest to open a shell window.

2. Type su to log in as root. Type in the root password if necessary.

3. Type at the prompt:

   cd /usr/lib/X11/input/config
   cp mouse.ptrmap mouse

4. Log out and log back in to reset the X server and make this change effective.

To return to vertical cursor movement, remove the /usr/lib/X11/input/config/mouse file, log out, then log back in.

Figure 3-1. Horizontal Cursor Movements

Controlling Window Manager Maximize Behavior

Because of the large logical display (1280 x 2048) of the dual channel option, some applications may use all of the available space and display a single window across both monitors. To get around this, you can control the maximum size of a window by modifying the window manager's default resource file as follows:

1. As root, use an editor such as NEdit to open the file /usr/lib/X11/app-defaults/4DWm.

2. Enter the following under 4Dwm Specific Appearance and Behavior Resources:

   *maximumMaximumSize: 1280x984

   This constrains the maximum window size to 1280 x 1024. The 40-pixel difference is for the title bar and the top and bottom window borders.

3. Save the file and exit the editor.

4. Restart the Window Manager. To do this, you can either log out and log back in, or choose System > Utilities > Restart Window Manager from the Toolchest, and click OK.

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Note: The method described here limits a maximized window's size, but does not necessarily position the window fully on one monitor or the other. After clicking the Maximize button, you can reposition the window to either monitor.

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Follow these instructions to select a display setting and enable dual channel mode.

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Note: These instructions are for IRIX 6.3. In later IRIX versions, Xscreen is replaced by Xsetmon. In Xsetmon, the next time you log out after changing the timing table or framebuffer depth, the existing X server resets itself and loads the new timing table and framebuffer depth before presenting the login screen.

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Note: Resolutions with a pixel clock below 50 MHz (for example VGA) are not supported in dual channel mode.

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To disable dual channel mode, select a setting that does not have a “2@” prefix and click Save & Apply. Click OK in the dialog box to kill the X server. Note that any windows you had open are lost. A new X server session is started and the display setting you chose is active. The login screen appears.

If you disable the dual channel display and both monitors are still connected, the same image is displayed on both monitors.

The dual channel display provides a single logical screen displayed vertically over two monitors. Most applications position their popup windows near their main window, or near the cursor.

However some applications center their popup windows. The dual channel display works as if the two monitors were a single logical display. If you're using an application that centers its popup window, in dual channel mode the window will overlap both displays vertically. The upper half of the window will be at the bottom of the left monitor, and the lower half at the top of the right monitor. See Figure 3-3.

To get around this, you need to modify the application's resources. See the instructions following the next figure.

Figure 3-3. Overlapping Windows

To launch an application in a specific location, add the “-geometry” option to the command line. For example, the following command opens a window with the upper left hand corner of the window 30 pixels from the left of the screen and 200 pixels from the top of the screen.

xterm -geometry +30+200

To place a window on the second display, add 1024 to the second number. For example:

xterm -geometry +30+1224

You can also set this X resource in $HOME/.Xdefaults. For example, the following command forces all xwsh windows to open with the upper left hand corner of the window 30 pixels from the left of the screen and 200 pixels from the top of the screen.

XWsh*geometry: +30+200

XWsh is the application's Classname.

Also, you can use the Window Setting Control Panel to set window locations explicitly or to their last (continuous) positions before logout. To do this, from the Toolchest choose Desktop > Customize > Windows.

When the mouse or tablet is configured for horizontal cursor movement between monitors, and you move a window from the left monitor to the right one, the window follows the cursor as it jumps between screens. However, as it moves across, the right edge of the window is clipped to the right edge of the left monitor, and the left edge is clipped to the left edge of the right monitor. Therefore the window doesn't move smoothly across, but appears to jump across when the cursor moves between monitors. See Figure 3-4.

Figure 3-4. Moving Windows Horizontally Between Monitors

Tablet devices are often configured to move the cursor in addition to the mouse. By default, the logical display area (1280x2048, vertical) is mapped to some part of the active area of the tablet. If you configured your mouse for horizontal cursor movement, you may wish to map the virtual display area (2560x1024, horizontal) to the tablet. To do this, you need to create a configuration file for the tablet with the following contents:

device_init {
   module   “ptrmap”
}

Create the file in the directory /usr/lib/X11/input/config. The filename must correspond to the module name for your tablet device as shown in the input(7) man page. For instance, for a Calcomp tablet, this file would be /usr/lib/X11/input/config/calcomp. You need root access to create files in this directory.

For tablet devices, pointer events are usually either scaled so that screen positions map to fit the full active area of the tablet, or to fit as close as possible while maintaining a 1:1 aspect ratio for X and Y values. The x_init control “scale” (which determines the appropriate scaling automatically) does not work as expected when the “ptrmap” module is associated with the device. Instead, set the “scalex” and “scaley” x_init controls to set the scale explicitly.

x_init controls are placed in a file in the directory /usr/lib/X11/input/config which is named according to the X name of the tablet device. For instance, for a Calcomp tablet, this file would be /usr/lib/X11/input/config/tablet.

If the horizontal resolution of a tablet is 9000 (perhaps a 9 inch wide tablet with 1000 line per inch resolution) and the virtual screen resolution is 2560x1024, the following configuration file contents enable the tablet as a pointer device and scale pointer events to use the whole width of the tablet:

x_init {
   pushpointer  “on”
   autostart    “on”
   scalewhich   “none”
   scalex       “2560/9000”
   scaley       “2560/9000”
}

Setting the same scaling factor for X and Y maintains a 1:1 aspect ratio. To scale to fit in the Y dimension as well, determine the scaling factor for Y in the same manner as described above for X.

For a Wacom tablet, both the module name and the X name are “wacom,” so a single configuration file named /usr/lib/X11/input/config/wacom is used for both the device_init and x_init statements. Also, the Wacom tablet driver automatically scales pointer events to fit the active area of the tablet, so it is not necessary to set the X and Y scaling factors in the configuration file. To configure the driver to maintain a 1:1 aspect ratio when scaling, use the following configuration file contents:

device_init {
   module      “ptrmap”
}
x_init {
   pushpointer  “on”
   autostart    “on”
   scalewhich   “none”
   rescale      “aspect”
}

For more information about input devices, input device configuration files, and device controls, see the input(7) man page.