If you are using QV10, then use the object Triggers On Activate and set the variable value. For example for table1 set the variable value vActiveTable = 1 when Table1 is made active. In Layout tab of Multi box use this expression
Show -> Conditional -> vActiveTable = 1
So, when you are clicking the Table1 the OnActivate event fires, during this we are changing variable value to 1. Based on this variable we are show/hiding the Multi List box by using Layout -> Show -> Conditional as said above.
I am not sure about QV11, in QV11 there are no object events concepts.
Hope this helps you.