get_display_style should not be used in add time tracking popup window
to reproduce:
1. click hide on issue details screen of time tracking
2. click show it again
3. click hide once again to set cookie being in state "do not show"
4. click add time tracking. you'll get add time tracking popup with just footer
--- eventum/templates/en/add_time_tracking.tpl.html~ 2006-02-10 13:33:45.000000000 +0200
+++ eventum/templates/en/add_time_tracking.tpl.html 2006-02-10 13:33:46.685081329 +0200
@@ -65,14 +65,14 @@