Created attachment 275704 [details]
Illustration of what happens in gedit when pressing backspace and delete keys with scim-m17n enabled

scim-m17n is used for typing many languages, especially those with complex characters. 

With scim-m17n is enabled, when one presses the backspace key, then instead of performing the expected work, the cursor simply moves one space ahead and places  "" there. Actually the sign is different from what appears here. When I paste it here, it is just an empty box. But there the box contains four digits arranged in two rows: "0008" for backspace, and "007F" for delete. I have attached a screenshot to illustrate more clearly.

With scim-m17n is enabled, when one presses the backspace key when gets a result equivalent to typing: <Ctrl+Shift+U> 0008 <Enter>

With scim-m17n is enabled, when one presses the delete key when gets a result equivalent to typing: <Ctrl+Shift+U> 007F <Enter>

This behaviour is evident only in gedit. When using scim-m17n in Libre Office, Thunderbird, and other applications, the backspace and delete keys work normally. 

In gedit with scim-m17n enable, all the other instructional keys like
insert, home, end, page up, page down-- these all work normally. 

I have been using scim-m17n since 2007, and this was never an issue until installing Ubuntu 14.04 which ships with gedit version 3.10.4.

This issue is a serious problem for those working with scim in gedit.