Hi Dawson,
I am unclear on what you are using the Palette element for, especially since there’s no documentation for this element. Also, this is not how test commands work: they are PennController commands, not boolean javascript functions.
I suspect that some element inside your HTML document turns white at some point, and you are trying to capture that change by using the Palette and Canvas elements, which are PennController elements. PennController elements are not HTML elements, and more particularly, creating a Canvas (PennController) element will not give you access to a <canvas> HTML element, even less so if the latter is embedded inside an iframe embedded in an HTML document.
If the task you are currently injecting through the Html element is the first screen of your experiment, I suggest you simply direct your participants to that page first, and insert a link at the end of your task that will direct them to your PCIbex experiment then. If it takes place in the middle of your experiment, I suggest you just insert a new-tab link pointing to your task’s page at that point, and maybe have your participants retrieve a code at the end of it that they will need to enter back into your PCIbex experiment in order to proceed.
Jeremy