Bug 4709 – REGRESSION: Ctrl+Backspace works incorrectly (please implement deleteBackwardByDecomposingPreviousCharacter)

• Status: NEW
• Component: HTML Editing

[Alexey Proskuryakov]

Steps to reproduce:
1. Launch Blot (example from /Developer/Examples/WebKit)
2. Type any decomposable character (such as é = option-e, e)
3. From Blot's Debug menu, select Show Operations
4. Click on deleteBackwardByDecomposingPreviousCharacter:

Results: the character disappears.
Expected results: only the accent should disappear.

Here is the relevant part from NSResponder documentation:

- (void)deleteBackwardByDecomposingPreviousCharacter:(id)sender

Implemented by subclasses to delete the selection, if there is one, or a single character backward from 
the insertion point. If the previous character is canonically decomposable, this method should try to 
delete only the last character in the grapheme cluster (for example, deleting “a�+ “´� results in “a�). The 
sender argument is typically the object that invoked this method. NSResponder declares but does not 
implement this method.

[Alexey Proskuryakov]

(the bug description should be viewed with encoding = UTF-8)

This can be also reproduced in Mail, Stickies etc. by pressing Ctrl+Backspace (which should do the same 
as deleteBackwardByDecomposingPreviousCharacter). In debugging builds, a message is logged: 

=================
ERROR: unimplemented, doing deleteBackward instead
(/Users/ap/WebKit/WebKit/WebView.subproj/WebHTMLView.m:4288 -[WebHTMLView 
deleteBackwardByDecomposingPreviousCharacter:])
=================

[Alexey Proskuryakov]

This has become a native text field regression, bumping priority to P1.

[Adele Peterson]

While this is a regression for native text fields, its an obscure enough feature that we want to leave it as P2.

[Alexey Proskuryakov]

Adding NeedsRadar keyword. I agree that this feature isn't particularly important for English (or Russian), but it might be vital for other languages.

[Mark Rowe (bdash)]

<rdar://problem/4928524>

[Alexey Proskuryakov]

Created attachment 15429 [details]
test case (DRT + manual)

[Justin Garcia]

This is now <rdar://problem/3655396>.

[Eric Seidel (no email)]

I assume this is a mac-specific bug?