I don't really use KDE for some reasons, and I don't know how skim and input methods work.
But I add a comment about input method. It's a copy of this bug report, sorry if it don't fit with KDE.
I submitted one in Gnome : http://bugzilla.gnome.org/show_bug.cgi?id=354247

Why not create an applet (icon in toolbar, systray  ?) for input method ?

- It would include IPA, Thai, chinese input methods, japanese input methods,
unicode value…
- It would be separated from keyboard layout applet.
- There would be a neutral value. In this case, only the characters on the
keyboard is usable, depend of the layout (french, US english, arabic…).
- The input method value would be memorized for the next reboot. If pinyin IM
is selected, at the next reboot, the pinyin IM will be aviable again. 
- The IM applet could be combined with keyboard layout applet. Input method can
work  with any keyboard layout. For example, chinese pinyin can work with
french keyboard, not only with US english keyboard.
- The IM applet would work with all applications : Gnome application,
OpenOffice, Firefox, KDE applications…
- …

Made an mistake in comment #2. Rewrite.

I don't really use KDE for some reasons, and I don't know how skim and input methods work in KDE applications. But I add a comment about input method.
It's a copy of a bug report for Gnome http://bugzilla.gnome.org/show_bug.cgi?id=354247.
Sorry if it don't fit with KDE.

Why not create an applet (icon in toolbar, systray ?) for input method ?

- It would include IPA, Thai, chinese input methods, japanese input methods,
unicode value…
- It would be separated from keyboard layout applet.
- There would be a neutral value. In this case, only the characters on the
keyboard is usable, depend of the layout (french, US english, arabic…).
- The input method value would be memorized for the next reboot. If pinyin IM
is selected, at the next reboot, the pinyin IM will be aviable again.
- The IM applet could be combined with keyboard layout applet. Input method can
work  with any keyboard layout. For example, chinese pinyin can work with
french keyboard, not only with US english keyboard.
- The IM applet would work with all applications : Gnome application,
OpenOffice, Firefox, KDE applications…
- … 

currently there's research is going in integrating IM with libxklavier, if that succeeds there's great chance it'll be included in kxkb in KDE4 

LIVINE Christin, thank you for your input. I give myself the permission to add your email on CC: to make sure you receive this.

actually, I really like your idea that you could use different input value with different keyboard layout. at the same time. I think it would be simpler (but yet less powerful) for the user to just set which keyboard layout you want to use which a specific input method. thus, on a single systray app or keyboard shortcut you could switch from fr-ca, fr-fr, en-us, ja, kr. instead of doing, ok, now I'm on fr-ca, I want to switch to ja, let's select the us layout first and the ja input method. I just want to switch from any to any in one click. I don't know if you use different keyboard layout for one input method but while it might be very handy to cover the needs of all user, one user is unlikely to use more than on keyboard layout for one input method. thus it should be a language settings not a choice on the UI. IMHO.

I read the report on gnome system and as far as I can understand, it seems the situation in KDE is already a bit better. the 'k' in skim might be scary but there is nothing evil here, its just a kde frontend to scim. It works fine, I can use japanese or any input method anywhere, Firefox, OO.org, G apps, K apps. The only thing is I would like it unified with KDE. being part of the standard distribution chances of bugs would be much lower. there is just so many input method choices and dependencies to scim. without talking about the competition (kinput, etc) which I don't know anything about. and the truth is, I already know more than I really wanted to.

as for french canadian keyboard, this is another issue, not really kde related. we are just the forgotton french nation in the world. Canada also have 2 official french canadian keyboard and finding the right settings on Linux/Unix is really a pain in the b**t.

you might want to check out the the other side of the world, for a sec, see how you like it ;)

About the idea of one applet for keyboard and one applet for input method, 

It seems that French typing has a input method, maybe in US English typing too
^^;
The use of dead keys means the use of input method ?

For example,
in the french keyboard, the character Ô (Latin capital letter O with
circumplex) can be generated by pressing first dead key ^ (Circumflex accent),
then O (Latin capital letter O).

It's like if I type japanese characters.

I really really really would like to see Skim integrated as well.

Skim, in my opinion, seems just to be a additionally added input method, which is not integrated nicely in KDE.

I am a German learning Japanese. Although I don't have to switch the normal keyboard layout, it really bugs me that Skim is not integrated in the system (e.g. skim does not work in all apps, especially gtk).

I think, the way it is handled in Windows is quite good and can be adopted without problems. Windows makes no difference between Input Mode Editors and ordinary Keyboard Layouts.

I would like if Skim (I don't know the other input methods, but as far as I know, Scim/Skim has a good modular basis) is integrated right at the basis in KDE. The Input Mode Editors should be left as indiviual programs (e.g. scim-anthy for KDE), but they should appear in KDE Control Center where you choose which Keyboard Layout you use.

Or, maybe, because I like the Skim switching tool, maybe there is a way to integrate the other normal Keyboard Layouts in Skim, so that you have a way to select everything you want, and not only one of them.

*** Bug 79815 has been marked as a duplicate of this bug. ***

*** Bug 157025 has been marked as a duplicate of this bug. ***

It would be great if it includes an unicode keyboard layout editor.
Easy to edit (graphical or in text file)
Easy to deploy.

An good example is Microsoft Keyboard Layout Creator (msklc
http://www.microsoft.com/globaldev/tools/msklc.mspx).

Maybe it already exist with Keyboard Mapping for Linux (kmfl
http://kmfl.sourceforge.net) ?

I don't know about Mac OS X…

Should I open a bug issue for that ?

There's a discussion about integrating IM into KDE keyboard module at kde-devel (http://lists.kde.org/?l=kde-devel&m=135916821104030&w=2) and also copied to kde-core-devel mailing lits. If anybody here still interested feel free to participate in it.

As for the keyboard layout editor it should be a separate bug.

I think my title could be simplified. my request is proposing an implementation.
as I was using skim....

but in fact, I don't care how it's done.

as of KDE 4.10, I can add JP as a list of keyboard... but even when I select it, I can't type in Japanese. so I'm not sure what is it suppose to do.

I am ok with adding this feature in. I don't know much about IM and don't use it but if somebody is willing to provide the patch I'll review it and will merge it in if it looks good.
My only condition (besides readable code :)) is to have a switch to turn this integration on/off.

I have said it elsewhere, but I'll repeat it here, at risk of making a fool of myself:
I have had nothing but good experiences with Fcitx (until the most recent overhaul of the keyboard layout system in Plasma 5). It integrates well (in part thanks to the modular design and the quality of the integrated configuration methods) and is very well polished. I realize there are probably good reasons why someone would use a different IME, but I would still recommend anyone to give it a whirl.

Note: I only use Fcitx for Japanese input, I don't know how good it is with Chinese, Korean, or other non-western input methods.

strangely, I had never heard of FCITX before Kubuntu 15.04 beta,
although it is there for quite some time...

it is a strange time to try it out, seems it is totally broken under Plasma 5

in the past, I have used SCIM with (skim client) for switching Japanese-English and the KDE subsystem for switching French-English. it has been annoying and so so working.

I stopped using SCIM a while ago and I am now very happy with ibus.
especially I can now do French, Japanese and English with ibus.

so at this time, I have keyboard switching in KDE disabled and ibus is doing the work.

the only problem I have left, is with kscreenlocker. should my screen lock with a keyboard different than English. I can not unlock my session and I need to reboot or kill my session somehow.

bummer

I have moved away from SCIM and IBUS

and I am now using fcitx

works OK
still a bit weird to switch French/English/Japanese but it works