correction. it actually does allow to edit templated trigger expressions, it's just that single expression is replaced, discarding the rest, and this change is saved
Fixed in dev branch: ZBX-1294
Button "Add" disabled for templated triggers
(1) "Toggle input method" should also be disabled.
(2) This is a different issue, but probably minor enough to be fixed here: if we toggle the input method and click on the expression two times, a popup appears that says "Do you replace the conditional expression?". Probably it is lacking the words "wish to"?
(1) "Toggle input method" is not present now for templated triggers
(2) String fixed
ZBX-1294disabled "Add" and "Toggle input method" for templated trigger expressions (KB)
[merged: branches/1.8 r15986]
In trunk rev 15989 is lost "Select prototype" button in 'popup_trexpr.php' 
Need to fix (return the button).
Oleksiy, thank you, fixed it.
hmm. i don't like disabling of "Toggle input method" for templated trigger expressions.
first, it removes the capability to see trigger in a visual way on the host level;
second, it removes the capability to test triggers with usermacros on the host level etc
it would be much better to disable individual controls in that editing mode.
(although this can also be added as a separate issue)
Ok, then we are:
- disabling buttons "Edit", "Insert macro", "And", "Or", "Replace"
- removing "Delete" column
- trigger link becomes inactive
Recreating development branch ZBX-1294
Changes are made in branch ZBX-1294
confirming the fix in dev branch rev 16072. leaving as is for code review
merged from branches/1.8 r16389