ControlContext :: showLevel - Show level
The show level (display level) for a control defines the display level, on which the control is visible. Controls with show level 0 are always visible. The display level set in the parent control (setDisplayLevel())decides, which subordinated controls are shown. E.g. setting the display level for the parent control to 1 will hide all subordinated controls that got a show level different from 0 and 1.
Return value: Display level ( int32 )
The display level is be a value greater or equal to zero. The value must not exceed the number of display levels in the control (e.g. the number of tabs in a tab control).
Display level 0 causes hiding all controls except those defined on level 0, which are visible on any display level.