We are experiencing the same issue as: https://getsatisfaction.com/pixelandtonic/topics/https_and_playa_in_cp
We're wanting to use the playa module along with force-ssl(http://devot-ee.com/add-ons/dm-force-ssl). Due to various constraints we were unable to apply SSL without this module.
The force-ssl module controls the "URL to your "themes" folder" among other variables. So despite setting it to /themes/ the playa plugin 'filter' feature still does not work.
We experienced the same issue with channel videos. After talking to them they were able to issue a patch that resolved this issue. We're wondering if you could also facilitate integration of the playa and force-ssl module?
I've also tried this and had the same result without force-ssl and just a simple rewrite for the control panel only:
RewriteCond %{HTTPS} off
RewriteCond $1 ^(admin.php) [NC]
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
Taylor
/themes/third_party/playa/...
orhttps://domain.com/themes/third_party/playa/...
?<link rel="stylesheet" type="text/css" href="/themes/third_party/playa/styles/field.css" />
And....<link rel="stylesheet" type="text/css" href="/themes/third_party/playa/styles/droppanes.css" />
<link rel="stylesheet" type="text/css" href="https://domain.com/themes/third_party/playa/styles/field.css" />