Child window not showing up in x11 - c++

Question

I have created two windows. One with 32 bit and the other with 24 bits. The 32 bit window renders opengl and creates graphics with an alpha component onto it. The 24 bit window renders video. Both of the windows are child of a main window which is 32 bits. To my knowledge, when I call XRestackWindows, it show stack the windows such that the 32 bit window is on the top while also showing the 24 bit window underneath. This is not the case. When I do so, it only shows the 32 bit window. I know the 24 bit window is there because if I switch the order, then I only get to see the 24 bit window. Why is this the case?
/* Open the standard display (the primary screen) */
x_display = XOpenDisplay ( NULL );
visual_template.screen = DefaultScreen(x_display);
visual_list = XGetVisualInfo(x_display, VisualScreenMask, &visual_template, &nxvisuals);
XMatchVisualInfo(x_display, XDefaultScreen(x_display), 32, TrueColor, &vinfo))
parent = XDefaultRootWindow(x_display);
XSync(x_display, True);
visual = vinfo.visual;
depth = vinfo.depth;
XSetWindowAttributes swa;
swa.event_mask = ExposureMask | PointerMotionMask | KeyPressMask;
swa.colormap = XCreateColormap(x_display, XDefaultRootWindow(x_display), visual, AllocNone);
swa.background_pixel = 0;
swa.border_pixel = 0;
main_window = XCreateWindow (
x_display, parent,
0, 0, m_plane_width, m_plane_height, 0,
depth, InputOutput,
visual, CWEventMask | CWBackPixel | CWColormap | CWBorderPixel,
&swa );
/* Create a window */
opengl_window = XCreateWindow (
x_display, main_window,
0, 0, m_plane_width, m_plane_height, 0,
depth, InputOutput,
visual, CWEventMask | CWBackPixel | CWColormap | CWBorderPixel,
&swa );
int cnxvisuals = 0;
XVisualInfo cvisual_template;
XVisualInfo *cvisual_list;
XVisualInfo cvinfo;
Visual *cvisual;
int cdepth;
cvisual_template.screen = DefaultScreen(x_display);
cvisual_list = XGetVisualInfo(x_display, VisualScreenMask, &cvisual_template, &cnxvisuals);
/* The gstreamer video sink must play on a screen with 24-bit color. Otherwise it will fail */
XMatchVisualInfo(x_display, XDefaultScreen(x_display), 24, TrueColor, &cvinfo)
XSync(x_display, True);
cvisual = cvinfo.visual;
cdepth = cvinfo.depth;
XSetWindowAttributes cswa;
cswa.event_mask = PointerMotionMask | KeyPressMask;
cswa.colormap = XCreateColormap(x_display, XDefaultRootWindow(x_display), cvisual, AllocNone);
cswa.background_pixel = 0;
cswa.border_pixel = 0;
/* Create the window */
gstreamer_window = XCreateWindow (
x_display, main_window,
0, 0, m_plane_width, m_plane_height, 0,
cdepth, InputOutput,
cvisual, CWEventMask | CWBackPixel | CWColormap | CWBorderPixel,
&cswa );
Window stack_position[2] = {opengl_window, gstreamer_window};
XRestackWindows(x_display, stack_position, 2);