#define GA_ROOT 2
// http://forum.mql4.com/ru/14463/page5#401551
#define MT4_WMCMD_ALL_HISTORY 33058
int main = GetAncestor(WindowHandle(Symbol(), Period()), GA_ROOT);
PostMessageA(main, WM_COMMAND, MT4_WMCMD_ALL_HISTORY, 0);
// http://forum.mql4.com/ru/14463/page5#401551
#define MT4_WMCMD_ALL_HISTORY 33058
int main = GetAncestor(WindowHandle(Symbol(), Period()), GA_ROOT);
PostMessageA(main, WM_COMMAND, MT4_WMCMD_ALL_HISTORY, 0);