Hello, I recently switched to the programmer dvorak keyboard layout and I think it's the one I want to use from now on.
I had some issues in changing the original layout, namely in making the new settings also effective in kdm: here is how I made it work through xorg.conf, but I'm not really convinced it's the right way.

Anyways, down to the kde problem. In dvp layout the numeric keypad should be in "phone order", that is 123 on the top row instead of 789. NumLock still works as usual, but you also get hex digits and other symbols you can type by holding shift when NumLock is on, and this is not working for me.
Example:

1. (NumLock off) numpad 2 --> arrow up
2. (NumLock on) numpad 2 --> 2
3. (NumLock on) shift + numpad 2 --> B

Point 2 only works if I check the "ATM/phone keypad" option in the advanced keyboard settings panel (otherwise I get 8 ), while I can't get point 3 to work at all. Funny thing is that after editing my xorg.conf I get the correct behaviour, but only in kdm.

So, the first problem is that I can't easily switch back to qwerty, because the ATM option is global and doesn't change as you click the flag in the tray bar. The same goes for the <> key, that must be set as a compose key in dvp.
The second problem is that I can't get the extra digits on the numeric pad to work at all.

Can somebody help me please?

Do the three listed items work correctly in KDM, using the Xorg method?
If they do, have you verified that the settings which KDE sets and the settings you are setting through the Xorg configuration match?

No, kde seems to override whatever I set in xorg. So now kdm works but not all the rest, not even the shell.

In kde, point 2 only works if I switch the ATM option on, which bothers me because if I click the tray flag to go back to qwerty I get reversed numpad.
Point 3 never works (except in kdm).

Have you tried disabling KDE Keyboard Layout handling in System Settings?

Not sure that's what you meant, I'm in "System settings -> input devices -> keyboard right now". In layouts I unchecked the Configure layouts and in advanced I unchecked the Configure keyboard options, then rebooted. This fixed the hex digits problem, though now I can't switch the layout back to qwerty.
If I re-enable the Configure layouts (no reboot), I can switch layout but I get the following problems:

1. ctrl+alt+backspace doesn't work anymore
2. when I switch to qwerty the numpad remains in dvp order (123 are on top row, I get hex numbers when I hold shift down)
3. in dvp I can't get 3rd level characters anymore if I do AltGr+C for example (I should normally get ç); 3rd level characters work in the qwerty layout (xorg mis-configuration?)
4. sometimes numlock led blinks, when I move the mouse towards the tray bar (keyboard flag is displayed there)

If I re-enable the "configure keyboard options" I get different settings in the advanced tab from what I had before rebooting, and the numpad still works as intended in the dvp layout (I imagine kde guessed those settings from X). So the only problem now is that advanced options don't switch as I switch layout. Problem 3 is solved by chosing Right alt as the 3rd level key, though 3rd level characters always work in qwerty, independently from this option.

It looks a little messy to me, mixing up the shortcut to kill X and the compose key position in the same place doesn't feel right, and some settings seem to be just ignored in certain layouts.
Also, the compose key correctly gets disabled as I switch to qwerty (although the "compose key position -> less/greater" remains checked). This is quite confusing... Maybe this area needs some reworking?

So, just for clearness sake, the problem I have now is that if I change to qwerty the numpad is reversed (ie the dvp numpad remains there).

Which version of KDE are you using? I think KDE 4.7 included quite a few changes to the KDE Keyboard Layout management ui. For the advanced settings I don't think you can have them setup differently depending on how you need them for individual layouts.

Also, have you tried different regional variants of Dvorak to see if they work any differently with your keyboard?

I'm using 4.8. My distro recently made 4.8.1 available, so I'm trying if there's any improvement asap.
I didn't try any other dvorak layout, but I'm under the impression that reversing the numpad is a dvp peculiarity (so no wonder that in Windows the dvp mapping is hacky and the numpad is half broken).

Those seem to be "normal" dvorak keyboards:
http://images.bit-tech.net/blog/2009/09 ... dvorak.jpg
http://shiar.nl/misc/dvorak/dvorakkb.jpg

Do you think I should file a bug about this? I can live with dvorak-only layout for the time being, just my girlfriend and anyone using my laptop won't be able to type anything right other than A. Not very funny after the first time :/

Thank you for helping me so far, at least I got the hex digits to work

Yes, you probably should file a bug - as the setup you produce using X should be reproducable using KDE's configuration tools.