how can i pass values to a custom sap.ui.model.type ?

hello,

i am building an app with side content panel. the size of the panel can be adjusted by a control.

i need to convert the width of the panel to a percent of the screen size.

i need to use a sap.ui.model.Type (... its a long story).

how can i pass a value (the current screen size) to the Type?

how can i work out the current screen size?

thanks for any help suggestions.

cheers

pas.