HI!
If use dhtmlxGrid + XCalendar and click calendar show behind the grid, grid z-index is higher than calendar;
How can i fix thnks
By default calendar has much greater z-index than a grid, probably you are using some container with high z-index.
This can be changed in dhtmlxcalendar.css
.dhtmlxcalendar{
background: url(imgs/cal_bg_single.png) no-repeat;
border: 0px solid green;
font-family: Arial;
z-index:99; // need to be increased
Beware that css contains few such settings for different skins