Ctrl-space shortcuts in applications don't work, for example in the NetBeans Java IDE for code completion, or in emacs (in a terminal) to set the mark. Reproducible: Always Steps to Reproduce: for NetBeans: 1. Install Oracle's JDK and the NetBeans IDE. 2. Edit a Java file and type ctrl-space for code completion. for emacs: 1. Install "emacs" package. 2. Open a text file with "emacs -nw". 3. Type ctrl-space to set the mark, then cursor-down to select a line, then alt-w to copy the line. Actual Results: for NetBeans: No effect, but alternate keybinding ctrl-\ works correctly. for emacs: Error message "The mark is not set now, so there is no region." If I drop down to a console (ctrl-alt-F1) and run emacs there, the key combination works normally. Expected Results: for NetBeans: Both ctrl-space and ctrl-\ should invoke auto-completion. for emacs: Line should be copied into the buffer without an error message. Ubuntu 14.04 "Trusty Tahr" daily build with all current updates applied.
What happens if you press Ctrl+Space? If applications do not see the combination, it is assigned as a global shortcut by some other program.
I went through the entire list of shortcuts in the "Shortcuts and Gestures" dialog of System Settings and did not find a binding for ctrl-space. Typing that combination by itself when the desktop has focus has no apparent effect. Is there a better way to see if there is a binding I didn't find?
I found what's causing it. Settings / Input Method shows that this combination is bound to "select next input method". However, when I change it to ctrl-alt-space, the next time I run the configurator, I get a dialog that says: Current configuration for the input method: * Active configuration: missing (normally missing) * Automatic configuration: ibus (normally ibus or fcitx or uim) * Number of valid choices: 2 (normally 1) The configuration set by im-config is activated by re-starting X. Explicit selection is not required to enable the automatic configuration if the active one is default/auto/cjkv/missing. Available input methods: ibus xim Unless you really need them all, please make sure to install only one input method tool.
I am not sure I understand comment #3. After your investigations, do you still see a bug in KDE software? If yes, could you be more specific to what the actual error is?
After re-assigning the Input Method key, shouldn't I see an active configuration? In the dialog that follows, I see this: "Do you explicitly select the user configuration? * Select NO, if you do not wish to update it. (recommended) * Select YES, if you wish to update it." Selecting YES results in the same dialog next time I run Settings / Input Method. Maybe I don't understand what this utility it supposed to do. If that's normal behavior, then the bug can be closed, since ctrl-space is no longer overridden. On the other hand, I have no idea what I might have done to get in that situation in the first place.
What is "Settings / Input Method" anyway? fcitx? KDE developers did not develop it, so if unsure, ask in a forum of your distribution who is responsible for this module. Marking as invalid, unless you can provide more information where KDE software has a bug.
It is im-config. You are right, as far as I can see it is Debian- or Ubuntu-specific.
Just a note to help other users resolve this (potentially annoying) problem. After upgrading to 12.04, I found that the Ctrl+Space keyboard shortcut was assigned to IBus' "Next Input Method", causing IBus to listen and capture Ctrl+Space while editing text. To clear the assigned IBus keyboard shortcut (and thus resolve the Netbeans editor Ctrl+Space code completion popup problem) you can edit IBus Preferences by running ibus-setup from the command prompt. Then delete the keyboard shortcut, or assign a different shortcut.