onclick events sometimes don't fire in drm with this fix

[grybouilli]

This has already been discussed in #227 and #759.

The initial issue was that onclick events didn't work at all on drm. In #227, a fix at b873e467 has been proposed for this initial issue; i cherry picked it (here), it works but sometimes, the onclick callback still won't fire.

I tried investigating it already but can't find the source of that problem. Any input on this? Has this issue been encountered with other backend like waylend or x11?

EDIT: I've tested this on wayland. The issue is present there too.