[PATCH 2/4] keyboard: Allow backspace for pre-edit text

[Bill Spitzak]

Jan Arne Petersen wrote:
> On 09/18/2012 02:29 AM, Bill Spitzak wrote:
>> I feel it would be better to confirm the pre-edit at this point, then
>> send the backspace to the application.
> 
> With a virtual keyboard one usually keeps the current word in the
> composing (pre-edit) state (to allow correction/prediction). I do not
> think committing would be the right strategy in this case.

If the remaining text is part of a precompose then I agree the current 
behavior is right. For instance if they typed "abc" (and this sequence 
of letters means something to the input method) and then typed 
backspace, the preedit should be changed to "ab".

If the remaining text is blank, then I think the application should 
handle it, by having the input method actually confirm the single 
character, then sending the backspace. For instance in a simple 
compose-prefix input method for latin languages, if the user types 
compose,a,backspace it should first show a preedit of 'a' (on the 
anticipation the user may type 'e' or an accent). When they type the 
backspace, it then "confirms" the 'a', then indicates that it did not 
use the backspace key.

The main reason for this behavior is so that Undo works as expected.