When we introduced pop-ups a few pages ago, we noted that you had to provide a positioner object when creating the pop-up. We asked you not to worry about it and just use the defaults, because it's a complicated interface and was beside the point. Now, we'll explore this complex interface in depth.
When you open a pop-up window, it's shown in a windowing system which has constraints that your client is not privy to. For example, Wayland clients are unaware of where their windows are being shown on-screen. Therefore, if you right click a window, the client does not possess the necessary information to determine that the resulting pop-up might end up running itself off the edge of the screen. The positioner is designed to address these issues, by letting the client specify certain constraints in how the pop-up can be moved or resized, and then the compositor, being in full possession of the facts, can make the final call on how to accommodate.
<request name="destroy" type="destructor"></request>
This destroys the positioner when you're done with it. You can call this after your pop-up has been created.
<request name="set_size"> <arg name="width" type="int" /> <arg name="height" type="int" /> </request>
The set_size request is used to set the size of the pop-up window being created.
All clients which use a positioner will use these two requests. Now, let's get to the interesting ones.