这些按钮为什么显示不出来

#include <windows.h>
#include <tchar.h>
 
LRESULT CALLBACK WinMessageProc(HWND hwnd,UINT msg,WPARAM wparam,LPARAM lparam);
 
int WINAPI _tWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPTSTR lpCmdLine,int nShowCmd)
{
    //First:Register a window
    WNDCLASSEX mwin;
    mwin.cbSize = sizeof(WNDCLASSEX);
    mwin.style = CS_VREDRAW | CS_HREDRAW;
    mwin.cbClsExtra = 0;
    mwin.cbWndExtra = 0;
    mwin.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    mwin.hCursor = LoadCursor(NULL,IDC_ARROW);
    mwin.hIcon = LoadIcon(NULL,NULL);
    mwin.hIconSm = LoadIcon(NULL,NULL);
    mwin.hInstance = hInstance;
    mwin.lpfnWndProc = WinMessageProc;
    mwin.lpszMenuName = NULL;
    mwin.lpszClassName = _T("DesktopCounter");
    if(!RegisterClassEx(&mwin))
    {
        MessageBox(NULL,_T("Error"),_T("Register error."),MB_OK);
        return 0;
    }
    //Second:Create this window
    HWND NewWindow = CreateWindowEx(0L,_T("DesktopCounter"),_T("DesktopCounter"),WS_OVERLAPPEDWINDOW,0,0,200,300,NULL,NULL,hInstance,NULL);
    if(NewWindow == NULL)
    {
        MessageBox(NULL,_T("Error"),_T("Create error."),MB_OK);
        return 0;
    }
    ShowWindow(NewWindow,nShowCmd);
    UpdateWindow(NewWindow);
    //Third:Message
    MSG msg;
    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }    
}
LRESULT CALLBACK WinMessageProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
    switch(msg)
    {
        case WM_DESTROY://exit
        {
            PostQuitMessage(0);
            break;
        }
        case WM_CREATE://begin
        {
            //0,1,2,3,4,5,6,7,8,9,.,c,+,-,*,/,and a line above these
            const int ButtonWidth = 50;
            const int ButtonHeight = 50;//square buttons
            RECT RC;
            GetClientRect(hwnd,&RC);
            HINSTANCE hInst = (HINSTANCE)GetWindowLongPtr(hwnd,GWLP_HINSTANCE);
            HWND NumButton1 = CreateWindowEx(0L,_T("Num1"),_T("1"),WS_VISIBLE|WS_CHILD,0,100,ButtonWidth,ButtonHeight,hwnd,(HMENU)1,hInst,NULL);
            HWND NumButton2 = CreateWindowEx(0L,_T("Num2"),_T("2"),WS_VISIBLE|WS_CHILD,50,100,ButtonWidth,ButtonHeight,hwnd,(HMENU)2,hInst,NULL);
            HWND NumButton3 = CreateWindowEx(0L,_T("Num3"),_T("3"),WS_VISIBLE|WS_CHILD,100,100,ButtonWidth,ButtonHeight,hwnd,(HMENU)3,hInst,NULL);
            HWND NumButton4 = CreateWindowEx(0L,_T("Num4"),_T("4"),WS_VISIBLE|WS_CHILD,0,150,ButtonWidth,ButtonHeight,hwnd,(HMENU)4,hInst,NULL);
            HWND NumButton5 = CreateWindowEx(0L,_T("Num5"),_T("5"),WS_VISIBLE|WS_CHILD,50,150,ButtonWidth,ButtonHeight,hwnd,(HMENU)5,hInst,NULL);
            HWND NumButton6 = CreateWindowEx(0L,_T("Num6"),_T("6"),WS_VISIBLE|WS_CHILD,100,150,ButtonWidth,ButtonHeight,hwnd,(HMENU)6,hInst,NULL);
            HWND NumButton7 = CreateWindowEx(0L,_T("Num7"),_T("7"),WS_VISIBLE|WS_CHILD,0,200,ButtonWidth,ButtonHeight,hwnd,(HMENU)7,hInst,NULL);
            HWND NumButton8 = CreateWindowEx(0L,_T("Num8"),_T("8"),WS_VISIBLE|WS_CHILD,50,200,ButtonWidth,ButtonHeight,hwnd,(HMENU)8,hInst,NULL);
            HWND NumButton9 = CreateWindowEx(0L,_T("Num9"),_T("9"),WS_VISIBLE|WS_CHILD,100,200,ButtonWidth,ButtonHeight,hwnd,(HMENU)9,hInst,NULL);
            HWND NumButton0 = CreateWindowEx(0L,_T("Num0"),_T("0"),WS_VISIBLE|WS_CHILD,50,250,ButtonWidth,ButtonHeight,hwnd,(HMENU)0,hInst,NULL);
            HWND NumButtonPoint = CreateWindowEx(0L,_T("Point"),_T("."),WS_VISIBLE|WS_CHILD,100,250,ButtonWidth,ButtonHeight,hwnd,(HMENU)10,hInst,NULL);
            HWND ChButtonPlus = CreateWindowEx(0L,_T("Ch_Plus"),_T("+"),WS_VISIBLE|WS_CHILD,150,150,ButtonWidth,ButtonHeight,hwnd,(HMENU)11,hInst,NULL);
            HWND ChButtonMinus = CreateWindowEx(0L,_T("Ch_Minus"),_T("-"),WS_VISIBLE|WS_CHILD,150,200,ButtonWidth,ButtonHeight,hwnd,(HMENU)12,hInst,NULL);
            HWND ChButtonMulti = CreateWindowEx(0L,_T("Ch_Multi"),_T("*"),WS_VISIBLE|WS_CHILD,150,100,ButtonWidth,ButtonHeight,hwnd,(HMENU)13,hInst,NULL);
            HWND ChButtonDivis = CreateWindowEx(0L,_T("Ch_Divis"),_T("/"),WS_VISIBLE|WS_CHILD,150,50,ButtonWidth,ButtonHeight,hwnd,(HMENU)14,hInst,NULL);
            HWND ChButtonEqual = CreateWindowEx(0L,_T("Ch_Equal"),_T("="),WS_VISIBLE|WS_CHILD,150,250,ButtonWidth,ButtonHeight,hwnd,(HMENU)15,hInst,NULL);
            HWND ChButtonPlomi/*Plus or Minus*/ = CreateWindowEx(0L,_T("Ch_Pl or Mi"),_T("+/-"),WS_VISIBLE|WS_CHILD,0,250,ButtonWidth,ButtonHeight,hwnd,(HMENU)16,hInst,NULL);
            HWND FucButtonClear = CreateWindowEx(0L,_T("Clear"),_T("C"),WS_VISIBLE|WS_CHILD,50,50,ButtonWidth,ButtonHeight,hwnd,(HMENU)20,hInst,NULL);
            HWND FucButtonBack = CreateWindowEx(0L,_T("Back"),_T("<-"),WS_VISIBLE|WS_CHILD,100,50,ButtonWidth,ButtonHeight,hwnd,(HMENU)21,hInst,NULL);
            break;
        }
        
        default:return DefWindowProc(hwnd,msg,wParam,lParam);
    }
    return 0;
}

练习用windows api做一个简单的计算器，还没做完想看效果，但是发现按钮一个都没有显示出来
测试之后发现按钮其实被创建了，但是没有显示（随便挑了一个按钮，发现不是NULL）
操作系统是Windows 10，开发工具用的是Dev-cpp，是c89标准
如果有更好的方案也请帮改进

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