Issue #1608878 by jessebeach, tim.plunkett, dead_arm, nod_, sun, effulgentsia, Everett Zufelt, geerlingguy: Added CTools dropbutton to core.

Issue #1057912 by bfroehle, mgifford, bowersox, tarekdj, geerlingguy, irunflower, hgurol: Fixed Weird Border on Vertical Tabs with Google Chrome and Safari caused by .element-invisible.

- Patch #1192044 by mjohnq3, Manuel Garcia, effulgentsia, sun, JohnAlbin, jessebeach, moshe weitzman: Convert Bartik's layout to mobile-first and responsive.

Issue #404302 by KrisBulman, kathyh, JamesAn, droplet, sun: Fixed Improve tabledrag grippie CSS (and fix an IE7 alignment issue).

Nate Lampton authored Oct 30, 2011 and catch committed Nov 01, 2011

Issue #22336 by quicksketch, scor, boombatower, and rfay. Move all core Drupal files under a core subdirectory.

#746470 by follow-up by aspilicious, Jacine, jbrown, sgabe, et al: Add border-radius for IE9 / Opera 10.50

#897638 by casey, sun, mgifford, et al: Allow .element-invisible to work with focusable elements like links.

- Patch #732914 by Jacine, sun, reglogge, cosmicdreams: improve the markup/CSS for content and user filter forms.

- Patch #718922 by derjochenmeyer, betz, mgifford, JohnAlbin, casey: .element-invisible does not work with VoiceOver on OS X Snow Leopard.

#448292 by Frank Ralf, David_Rothstein, mgifford, Everett Zufelt, Bojhan, mohammed76, et al: Fixed Drag and Drop for table rows is not accessible to screen-reader users.

- Patch #676800 by casey, sun, james.elliott, cosmicdreams, seutje, Jacine: made fieldsets work on all browser.

#592018 by mverbaar, Jacine, et al: Re-organize styles across stylesheets from system.module and separate presentational and behavior-supporting styles.