Volume 6A: Motif Programming Manual

17.2.1 Shell Positions

You can position a shell at a specific location on the screen using the XmNx and XmNy resources. In addition, you can

set the XmNx and XmNy resources of the immediate child of a shell widget to position the shell. This feature exists

because Motif dialogs are designed to make their shell widgets invisible to the programmer. It is typically easier to set

these resources directly on the child of a shell, as you are more likely to have a handle to that widget. The following

code fragment shows how you can position a MessageDialog in the center of the screen:

Widget dialog, parent;

Dimension width, height;

Screen screen = XtScreen (parent);

Position x, y;

dialog = XmCreateMessageDialog (parent, "dialog", NULL, 0);

/* get width and height of dialog */

XtVaGetValues (dialog,

XmNwidth, &width,

XmNheight, &height,

NULL);

/* center the dialog on the screen */

x = (WidthOfScreen (screen) / 2) − (width / 2);

y = (HeightOfScreen (screen) / 2) − (height / 2);

XtVaSetValues (dialog,

XmNx, x,

XmNy, y,

NULL);

You can position a dialog in this way because the Motif BulletinBoard widget passes positional information to its

shell parent. See Chapter 5, Introduction to Dialogs, and Chapter 7, Custom Dialogs, for further discussion. In most

cases, you shouldn't be setting the XmNx and XmNy resources for a dialog because it is the job of the window manager

to position shells. The user can also have some say in how placement should be handled. For example, if the user has

set the interactivePlacement ...