When a widget instance is created, all of its public variables are
initialized by the Tix Intrinsics before the
InitWidgetRec method is
InitWidgetRec and any other method of this widget
instance are free to assume that all the public variables have been
properly initialized and use them as such.
The public variables are initialized by the following criteria:
tixArrowButton .arr -direction n
n will be used for the -direction variable.
option add *TixArrowButton.direction w tixArrowButton .arr
w will be used for the -direction variable.
You can use a type ckecker procedure to check whether the user has supplied a value of the correct type for a public variable. The type checker is specified in the -configspec section of the class declaration after the default value.