|Changes the enabled state of a menu item.
VarioMenuItem.Enabled = boolean
boolean - When is true the menu item is enabled, when
false - disabled.
Enabled and disbaled states of a menu item are indicated in the normal manner - by
displaying the item's caption grayed. When item is disbaled, it can't be seleced and click
function is not called.
Enabled property has no sence for separators and radio group holder items and setting
its value on them causes an error. Each member of a radio group can be enabled or disabled
by this property.