This is the button that expands or contracts a node (if applicable),
and EXP-BUTTON-CHAR the character in it (+, -, ?, etc). EXP-BUTTON-FUNCTION
is the function to call if it's clicked on. Button types are
This is the button that expands or contracts a node (if applicable),
and EXP-BUTTON-CHAR the character in it (+, -, ?, etc). EXP-BUTTON-FUNCTION
is the function to call if it's clicked on. Button types are