Limiting work on translated strings in po files with GNU Emacs

[Alexander Shopov <ash@contact.bg>]

Hi guys,
I am using the po-mode of GNU Emacs to make translations of gettext-ized 
packages.
Sometimes I do massive search and replace, changing or seeking in the 
translated strings.
Po-mode does not let me do that - entering po-mode leads to making the 
whole buffer readonly. Translations are edited then one by one.
When I press E in po-mode, I get to have the whole buffer in read-write 
mode.
What I want to have is the po-mode buffer magically enter a state where 
most commands like query-replace, query, or their regexp versions, work 
only on the translated strings (msgstr), as if the original text 
extracted from the file (msgid) do not exist at all. Still - they should 
pe preferably shown.

For example, given a buffer that contains:

msgid "Apple"
msgid_plural "Apples"
msgstr[0] "Elp"
"pa"
msgstr[1] "Sel"
"lpa"

line 1 and 2 should be readonly and not queriable, seekable, etc.
line 3,4,5,6 should be seekable and modifiable.
It will be even better if only the translated strings should be 
modifiable, taking account of the possible ways of breaking the line. 
This is optional as the translation can be reformatted.

Best regards:
al_shopov