Go here to get some simplified X Window and X Toolkit Intrinsics Documentation on calls used in this example

Create a file named "demo_xt3.cpp" with the contents shown in the box (the changes from demo_xt2.cpp are highlighted):

#include <X11/IntrinsicP.h> // IntrinsicP.h has some faster macros than Intrinsic.h #include <X11/ShellP.h> // Needed for Widget class definitions #include <stdio.h> //fprintf, stderr XtAppContext app; Widget main_widget; //Main Window Display *main_disp; //The Display pointer for the parent widget is stored here. Window main_wind; //The Window for the parent widget is stored here. //------------------------------------------------ // This function is called by a ButtonPress event in the main widget // Button 1 is the loft mouse button, Button 3 is the right button, // Button 2 is the middle button (or the left & right button pressed together) // Button 3 quits the program void EvProc(Widget w, XtPointer client_data, XEvent *event, char* CTmp) { if (event->xbutton.button == Button1) fprintf(stderr, "Button 1 Pressed\n"); if (event->xbutton.button == Button2) fprintf(stderr, "Button 2 Pressed\n"); if (event->xbutton.button == Button3) { fprintf(stderr, "Button 3 Pressed\n"); exit(0); } } //------------------------------------------------ void main (int argc, char **argv) { short unsigned int xx,yy; Colormap cmap; XColor color; //--- Create and initialize the top-level widget main_widget = XtOpenApplication(&app, "My Application", NULL, 0, &argc, argv, NULL, applicationShellWidgetClass, NULL, 0); //--- Make it the desired size XtMakeResizeRequest(main_widget, 300, 100, &xx, &yy); //--- Realize the main widget XtRealizeWidget(main_widget); //Save main widget Window & Display values main_wind = XtWindow(main_widget); main_disp = XtDisplay(main_widget); //--- Load default colormap and allocate a color close to the desired background color cmap = DefaultColormap(main_disp, DefaultScreen(main_disp)); if (XParseColor(main_disp, cmap, "dark_blue", &color) == 0) fprintf(stderr, "Bad Parse\n"); if (XAllocColor(main_disp, cmap, &color) == 0) fprintf(stderr, "Bad Color\n"); XSetWindowBackground(main_disp, main_wind, color.pixel); //--- Add Mouse Button Event Handler XtAddEventHandler(main_widget, ButtonPressMask, FALSE, EvProc, NULL); //----- XClearWindow(main_disp, main_wind); XtAppMainLoop(app); }

Change the Makefile file from Example 2 to use demo_xt3
To compile and link this program, type
make
This will compile and link demo_xt3.cpp into the executable file demo_xt3
Now type
demo_xt3 (you may have to enter the complete path)
and a window with a background color should now appear.