Help with VM

Quick Background
Working on a making a VM that can run on Blackberry phones. The VM itself was created by someone else and my job now is to port the display primitives to Qt. So far we have all the graphics appearing for the small talk applications we are using.
The Problem/Question
I have run into an issue when it comes to objects that require user input. Take a button for instance. When the button is created on the screen it is not done by calling for a single primitive but instead is usually made from drawing several rectangles, inputting some text and so forth. When the button is drawn, there are no “responsive” features, instead it is just a pixmap. My knowledge in regards to the VM and small talk in general is rather limited so I had a few questions.
Is their supposed to be a mask generated as well that overlaps the pixmap to detect for button presses?
Or is the VM supposed to interpret buttons differently than other graphics?
The same thing happens for input fields. It draws the field and even the cursor that indicates you should input something, however they are drawn in a static pixmap and can’t be interacted with.