Simple and fast question:
Tried to add a placeholder to appear next to the "select all" checkbox but it doesn't work... tried with and without filter. Any workaround to add a label to the select all checkbox?
Thanks! 
You are right. Currently there is no way to set placeholder for filter input nor select all text if the filtering is turned off. We will make Placeholder property to work exactly this way in our next update.
No worries, people can do it with some CSS
Thanks for the heads up!