Used to parameterize callback specified by handler
container
Container to attach widget to
…
Passed to add method of container.
toolkit
Which GUI toolkit to use
Details
The svalue method returns the current filename.
The svalue<- method can be used to set a new file to display.
The addhandlerclicked(obj, handler, action, ...) method where handler has
first argument h has the additional values h\$x and
h\$y where these are pixel values for where the mouse click occurred.