Child window does not get created - c++

Question

EDIT : Now this is strange, if I move the call to jItems::populate ( std::string myList ) to the constructor of jDropDown::jDropDown from else where in the jDropDown::jDropDown, the child windows get created.
Originally its been called when the dropdown(jDropDown) window is made visible(shown), and the flow of the program doesn't allow a call to jItems::populate ( std::string myList ) be moved to constructor of jDropDown::jDropDown.
What I an trying to do is create a custom Dropdown box from scratch, the problem I am facing is the final Items(jItem) windows are not created, its an oop design and
every Items(jItem) is derived from jPanel, the other parts of the dropdown box are also drived from jPanel so creating each and every window follows the same process yet the final
Items(jItem) windows are not created, they are not visible and I can't find them with visual studio Spy++
I have checked for instance handle and window handle, and both the checks returns true, yet the jItem windows are not visible and can't find them in spy++ (I can see all the other windows in spy++)
Any help is appreciated.
Here is a reference image and some relevant code.
bool jPanel::registered = false;
jPanel::jPanel( std::string txt, int x, int y, int width, int height, HWND parent, HINSTANCE hInstance, WORD bitmap, DWORD style )
: jControl( parent, hInstance, bitmap )
{
if ( ! registered )
{
WNDCLASSEX wincl;
wincl.hInstance = hInstance;
wincl.lpszClassName = "jPanel";
wincl.lpfnWndProc = WndProc;
wincl.style = CS_BYTEALIGNWINDOW;
wincl.cbSize = sizeof ( WNDCLASSEX );
wincl.hIcon = 0;
wincl.hIconSm = 0;
wincl.hCursor = ::LoadCursor ( NULL, IDC_ARROW );
wincl.lpszMenuName = NULL;
wincl.cbClsExtra = 0;
wincl.cbWndExtra = 4;
wincl.hbrBackground = ::CreateSolidBrush ( backgroundColor );
::RegisterClassEx ( &wincl );
jPanel::registered = true;
}
DWORD flag = WS_CLIPCHILDREN | WS_CLIPSIBLINGS | WS_CHILD;
if ( style ) flag = flag | style;
hwnd = ::CreateWindowEx ( 0, "jPanel", txt.c_str ( ), flag, x, y, width, height, parent, 0, hInstance, ( LPVOID ) this ) ;
};
jDropDown::jDropDown ( std::string txt, int x, int y, int width, int height, HWND parent, HINSTANCE hInstance, WORD bitmap )
: jPanel ( txt, x, y, width, height, parent, hInstance, bitmap ), capture ( false ), populated ( false )
{
RECT rect;
::GetWindowRect ( hwnd, &rect );
::MapWindowPoints ( HWND_DESKTOP, ::GetParent ( parent ), ( LPPOINT ) &rect, 2 );
items = new jItems ( "My Items List", rect.left, rect.top + height, width, 300, ::GetParent( parent ), hInstance, 0 );
items->setBackgroundColor ( RGB ( 100, 100, 100 ) );
};
jItems::jItems ( std::string txt, int x, int y, int width, int height, HWND parent, HINSTANCE hInstance, WORD bitmap )
: jPanel ( txt, x, y, width, height, parent, hInstance, bitmap ), wWidth ( width ), wHeight ( 30 )
{
::SetWindowPos ( this->hwnd, HWND_TOP, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE );
};
bool jItems::populate ( std::string myList )
{
int y = 0;
Hinstance hInstance = ::GetModuleHandle ( NULL );
std::vector < std::string > list = model::Service::explode ( "^", myList );
for ( std::vector < std::string >::const_iterator it = list.begin ( ); it != list.end ( ); ++it )
{
std::string s = *it;
jItem *i = new jItem ( "Your Item", 0, y, wWidth, wHeight, this->hwnd, hInstance, 0 );
}
::SetWindowPos ( this->hwnd, HWND_TOP, 0, 0, wWidth, list.size ( ) * wHeight, SWP_NOMOVE | SWP_NOZORDER );
return true;
};
jItem::jItem ( std::string txt, int x, int y, int width, int height, HWND parent, HINSTANCE hInstance, WORD bitmap )
: jPanel ( txt, x, y, width, height, parent, hInstance, bitmap ), empty ( false )
{
this->setBackgroundColor ( RGB ( 65, 65, 65 ) );
};