I have one webusercontrol for Datepicker. When I am using this control in content pages it works fine. I have many controls in content page (textbox, label, etc.). All controls are inside a table. I have placed usercontrol inside <td>. When I click on an image, the calendar control is showing. But that time this calender control pushes all other controls (textbox, label, etc.). I have set the z-index at a higher value, but still it's not working.
Z-index will not work for you becuase it is made for absolute,fixed and relative positioned elements. in your case what happened is when the calendar was not loaded the cell was empty but when you opened the calenday it filled the cell and expanded the row which it expanded the table. which causes the elements who are inside the tabe to change their position. try not to put the calendar over the other rows. create new column. set rowspan and put the calendar inside that cell which it will expand in its cell with out affecting the other rows since it is in different column (this will change the desiegn but it is the easy way)