Controls disappearing when a message box appears C++ GTK - c++

Question

I have programed the GUI in C++.
#include <gtk/gtk.h>
#include <unistd.h>
#include <cstddef>
#include <iostream>
#include <string>
#include <stdio.h>
#include <stdlib.h>
int main(){
GtkWidget *_LinuxWindow, *_Box, *_Button;
int argC = 0;
char** argV;
// Setup the window and fixed grid
gtk_init(&argC,&argV);
_LinuxWindow = gtk_window_new(GTK_WINDOW_TOPLEVEL);
_Box = gtk_fixed_new();
// Set the title
gtk_window_set_title(GTK_WINDOW(_LinuxWindow),"Title");
// Finish up
gtk_widget_show(_LinuxWindow);
g_signal_connect(G_OBJECT(_LinuxWindow),"destroy",G_CALLBACK(gtk_main_quit), NULL);
// Add controls
_Button = gtk_button_new_with_label("Click Me!");
gtk_fixed_put(GTK_FIXED(_Box),_Button,20,20);
gtk_fixed_move(GTK_FIXED(_Box),_Button,20,20);
gtk_widget_show(_Box);
gtk_widget_set_size_request(_Button,30,100);
// Create a dialog
GtkWidget *dialog;
dialog = gtk_message_dialog_new(GTK_WINDOW(_LinuxWindow), GTK_DIALOG_DESTROY_WITH_PARENT,GTK_MESSAGE_INFO,GTK_BUTTONS_OK_CANCEL,"OK or Cancel?",NULL,g_strerror(errno));
gint ret = gtk_dialog_run(GTK_DIALOG(dialog));
gtk_widget_destroy(GTK_WIDGET(dialog));
printf("%i", ret);
// Add the fixed grid and go the to the main window loop
gtk_container_add(GTK_CONTAINER(_LinuxWindow),_Box);
gtk_widget_show(_Box);
gtk_widget_show_all(_LinuxWindow);
gtk_main();
return 0;
}
When I run it using
g++ -o out-withoutCross without-cross.cpp -lX11 `pkg-config --cflags gtk+-3.0`pkg-config --libs gtk+-3.0`
A message box and a window appears. The problem is the controls in the window do not appear while the message box is open. I think this may be because the message box is being ran on the same thread that the main window is. Is there any way to add multi-threading to GTK?
Also the return value of the message box printed to console is running after the main window is exited.

Answer 1

The problem is the structure of your code..\
#include <gtk/gtk.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main() {
GtkWidget *_LinuxWindow, *_Box, *_Button;
int argC = 0;
char **argV;
// Setup the window and fixed grid
gtk_init(&argC, &argV);
_LinuxWindow = gtk_window_new(GTK_WINDOW_TOPLEVEL);
_Box = gtk_fixed_new();
// Set the title
gtk_window_set_title(GTK_WINDOW(_LinuxWindow), "Title");
// Finish up
gtk_widget_show_all(_LinuxWindow);
g_signal_connect(G_OBJECT(_LinuxWindow), "destroy", G_CALLBACK(gtk_main_quit),
NULL);
// Add controls
_Button = gtk_button_new_with_label("Click Me!");
gtk_fixed_put(GTK_FIXED(_Box), _Button, 20, 20);
gtk_fixed_move(GTK_FIXED(_Box), _Button, 20, 20);
gtk_widget_set_size_request(_Button, 30, 100);
gtk_container_add(GTK_CONTAINER(_LinuxWindow), _Box);
gtk_widget_show_all(_LinuxWindow);
// Create a dialog
GtkWidget *dialog;
dialog = gtk_message_dialog_new(
GTK_WINDOW(_LinuxWindow), GTK_DIALOG_DESTROY_WITH_PARENT,
GTK_MESSAGE_INFO, GTK_BUTTONS_OK_CANCEL, "OK or Cancel?", NULL);
gint ret = gtk_dialog_run(GTK_DIALOG(dialog));
gtk_widget_destroy(GTK_WIDGET(dialog));
printf("%i", ret);
// Add the fixed grid and go the to the main window loop
gtk_main();
return 0;
}
gtk_dialog_run is a blocking function so it will wait until it gets a response from the dialog box.. to proceed further
In your code, you are adding the button to the window only after running the dialog box window (which is a blocking call) so after its execution, the button is being added to the window