#define STRICT
#include <windows.h>

struct KZ_Data {
        WNDPROC oldWndProc;
        int subs;
        HWND sub[20];
};

static KZ_Data * __loadds GetKZ_Data(HWND hwnd) {
        HGLOBAL hglob=(HGLOBAL)GetProp(hwnd,"KZ_Data");
        if(hglob==0) return 0;
        void FAR *ptr = GlobalLock(hglob);
        return (KZ_Data *)ptr;
}

static void __loadds ReleaseKZ_Data(HWND hwnd) {
        HGLOBAL hglob=(HGLOBAL)GetProp(hwnd,"KZ_Data");
        if(hglob==0) return;
        GlobalUnlock(hglob);
}

static void __loadds DestroyKZ_Data(HWND hwnd) {
        HGLOBAL hglob=(HGLOBAL)GetProp(hwnd,"KZ_Data");
        if(hglob==0) return;
        GlobalFree(hglob);
        RemoveProp(hwnd,"KZ_Data");
}

static KZ_Data *CreateKZ_Data(HWND hwnd) {
        HGLOBAL hglob = GlobalAlloc(GMEM_MOVEABLE,sizeof(KZ_Data));
        if(hglob==0) return 0;
        void FAR *ptr = GlobalLock(hglob);
        if(ptr==0) {
                GlobalFree(hglob);
                return 0;
        }

        if(!SetProp(hwnd,"KZ_Data",hglob)) {
                GlobalUnlock(hglob);
                GlobalFree(hglob);
                return 0;
        }

        KZ_Data *p=(KZ_Data *)ptr;
        p->oldWndProc=0;
        p->subs=0;
        return p;
}

LONG CALLBACK KZ_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
        if(msg==WM_ACTIVATE) {
                KZ_Data *p=GetKZ_Data(hWnd);
                if(!p) goto def;

                if(wParam!=WA_INACTIVE) {
                        HWND hwndBehind;
                        hwndBehind = GetWindow(hWnd,GW_HWNDPREV);
                        if(hwndBehind==NULL) hwndBehind=HWND_TOP;
                        for(int i=0; i<p->subs; i++) {
                                if(IsWindow(p->sub[i])) {
                                        SetWindowPos(p->sub[i],hwndBehind,0,0,0,0,SWP_NOMOVE|SWP_NOSIZE|SWP_NOACTIVATE);
                                } else {
                                        for(int j=i; j<p->subs-1; j++)
                                                p->sub[j]=p->sub[j+1];
                                        p->subs--;
                                        i--;
                                }
                        }
                }
                ReleaseKZ_Data(hWnd);
        }
        if(msg==WM_NCDESTROY) {
                KZ_Data *p=GetKZ_Data(hWnd);
                WNDPROC wp=p->oldWndProc;
                ReleaseKZ_Data(hWnd);
                DestroyKZ_Data(hWnd);
                if((WNDPROC)GetWindowLong(hWnd,GWL_WNDPROC)==KZ_WndProc)
                        SetWindowLong(hWnd,GWL_WNDPROC,(LONG)wp);
                return CallWindowProc(wp,hWnd,msg,wParam,lParam);
        }
def:
        KZ_Data *p=GetKZ_Data(hWnd);
        WNDPROC wp=p->oldWndProc;
        ReleaseKZ_Data(hWnd);
        return CallWindowProc(wp,hWnd,msg,wParam,lParam);
}

extern "C" UINT CALLBACK __export KeepWindowAbove(HWND hwnd, HWND hwndAbove) {
        KZ_Data *p=GetKZ_Data(hwndAbove);
        if(!p) {
                p=CreateKZ_Data(hwndAbove);
                if(!p) return 1;
                p->oldWndProc = (WNDPROC)SetWindowLong(hwndAbove,GWL_WNDPROC,(LONG)KZ_WndProc);
        }
        for(int i=0; i<p->subs; i++)
                if(p->sub[i]==hwnd)
                        return 2;
        if(p->subs>=20)
                return 3;
        p->sub[p->subs++]=hwnd;
        ReleaseKZ_Data(hwnd);
        return 0;
}

int CALLBACK LibMain(HINSTANCE, WORD, WORD, LPSTR) {
        return 1;
}