An application sends a ZGM_ISGRIDDIRTY to determine if a value or an attribute of the grid has been changed.
ZGM_ISGRIDDIRTY
wParam = (WPARAM) (BOOL) fEnable; //enable flag
lParam = 0; //not used; must be zero
A boolean value indicating whether or not the grid is "dirty". A dirty grid means that a value or attribute of the grid has changed and a grid save operation may be necessary.