|This idea has been developed and deployed to the Canvas Community|
If voting on ideas is intended to guide decisions of Canvas support people, it makes no sense to close votes. Closing off votes on a particular date implies that (a) everyone who might care about the idea will look find it during the voting period, or (b) opinions of people who don't find the idea during the voting period don't matter.
These assumptions are reasonable only if you assume that all of the Canvas users who you want to serve are ones who regularly come to the Canvas support page and peruse or search the ideas forum looking for new ideas. Surely there are more Canvas users who don't do that than those who do.
Having timed forums is simply a poor way to gauge user interest. It's like holding an election and only telling political junkies where the polls are.
If you leave voting open, you'll still miss the opinions of those who never come to the forum, but leaving voting open at least doesn't exclude those who occasionally search for ideas that they care about. If you really want to guide decisions about the product using user feedback, you should want as much feedback as possible. (That should include opinions gleaned by front-line support people from users asking questions who don't necessarily follow up by going to the forum.)
(An added benefit: You won't frustrate users who find an idea after its voting period has closed!)