Comment 7 for bug 224309

Add following functions to pcmanfm-0.3.2.2/src/main.c => static void check_icon_theme()

static void check_icon_theme()
{
    GtkSettings * settings;
    char* theme;
    const char* title = N_( "GTK+ icon theme is not properly set" );
    const char* error_msg =
     ..................
    settings = gtk_settings_get_default();

/*****Set "gtk-icon-theme-name" to "gnome" ****/
g_object_set( settings, "gtk-icon-theme-name","gnome", NULL );

/****Get icon theme from settings*******/
g_object_get( settings, "gtk-icon-theme-name", &theme, NULL );

    /* No icon theme available */
    if ( !theme || !*theme || 0 == strcmp( theme, "hicolor" ) )
       ..............
}

then it can switch icon theme from hicolor to gnome.