The Dictionary panel (Command-Control-D) doesn't work correctly on text in a transformed element. It seems to refuse to open up. I'm guessing it's related to the relative positions of the cursor and the reported selection rects.
Created attachment 25660 [details] Testcase
The relevant call stack is #3 0x038bc680 in WebCore::RenderText::caretRect (this=0x1c90d00c, inlineBox=0x1c90a20c, caretOffset=25, extraWidthToEndOfLine=0xbfffdc1c) at /Volumes/Cassoulet/WebKit/WebKit.git/WebCore/rendering/RenderText.cpp:388 #4 0x035a4eef in WebCore::Frame::firstRectForRange (this=0x99fac0, range=0x1aff2480) at /Volumes/Cassoulet/WebKit/WebKit.git/WebCore/page/Frame.cpp:271 #5 0x001aff54 in -[WebFrame(WebInternal) _firstRectForDOMRange:] (self=0x99fb10, _cmd=0x26e514, range=0x1af9ecd0) at /Volumes/Cassoulet/WebKit/WebKit.git/WebKit/mac/WebView/WebFrame.mm:681 #6 0x001b1382 in -[WebFrame(WebInternal) _characterRangeAtPoint:] (self=0x99fb10, _cmd=0x25fe92, point={x = 179, y = 25}) at /Volumes/Cassoulet/WebKit/WebKit.git/WebKit/mac/WebView/WebFrame.mm:973 #7 0x001cbd87 in -[WebHTMLView(WebNSTextInputSupport) characterIndexForPoint:] (self=0x1aff5170, _cmd=0x94418798, thePoint={x = 179, y = 25}) at /Volumes/Cassoulet/WebKit/WebKit.git/WebKit/mac/WebView/WebHTMLView.mm:4963 #8 0x95772c6b in _NSTSMEventHandler () So this depends on the caretRect stuff.
Note: the "start and end are on the same line" test in Frame::firstRectForRange() is wrong for transformed elements. But fixing this still doesn't make it work in all cases.