Created attachment 278686 [details]
Screenshots

If between gtk_status_icon_set_from_file() and gtk_main() was too much time. Tray icon appears with no image. 

Steps to reproduce:
1) Use this code

#include <gtk/gtk.h>
#include <unistd.h>
#define SLEEP_TIME 1

int main(int argc, char **argv)
{
	gtk_init(&argc, &argv);
	GtkStatusIcon *tray_icon;
	tray_icon = gtk_status_icon_new();
	gtk_status_icon_set_from_file(tray_icon, argv[1]);
	gtk_status_icon_set_visible(tray_icon, TRUE);
	printf("Wait\n");
	sleep(SLEEP_TIME);
	printf("Do!\n");
	gtk_main();
	return 0;
}

2) Compile with 
        $ g++ ./main.cpp `pkg-config --cflags --libs gtk+-2.0` -o gtk2_sleep1
3) run: 
        $ ./gtk2_sleep1 <PATH_TO_ICON>; 

Expected result: icon shows in tray with image .
Actual result: Icon shoes in tray with no image. (see gtk2_sleep1.png in attachments)

If setup SLEEP_TIME to 0, icon shows successfully. (see gtk2_sleep0.png in attachments)

If compile with:
g++ ./main.cpp `pkg-config --cflags --libs gtk+-3.0` -o gtk3_sleep1

Icon shows with small image. (see gtk3_sleep1.png and gtk3_sleep0.png in attachments)