C++
afx_msg void OnUpdateThumbnailCheck();
Description
This method is the message handler for the update thumbnail checkbox. It updates the state of the checkbox when the checkbox is selected. If the UPDATETHUMBNAIL sysvar is currently set to either 0 or 7, the checkbox will behave as a normal two-state checkbox. If the sysvar is set to a value between 1 and 6, then the checkbox will behave as a tri-state checkbox.