issues with tying a dotted quarter to an eighth note

Works fine for me.
Check out this section: http://musescore.org/en/handbook/tie
If you still can't get it, post what specifically you're clicking on/typing so we can pinpoint what you're doing wrong.

I can reproduce, but the problem is another one, I think.

A method that works:
- select last note (Gb)
- enter note entry mode: "n"
- enter a Gb: "g" NUM-minus
- select dotted quarter note: NUM-5 NUM-dot
- add tie: hit NUM-plus
result: Gb eighth with tied dotted quarter note

When you tried the above, please reopen the file, or you can get an "cmdAddTie: has already tie?" from line 870, which is another thing.

What doesn't work, is:
- select rest after last note
- create dotted quarter Gb as above: "n" NUM-5 NUM-dot "g" NUM-minus
- select previous note: CUR-left
- exit note entry mode: ESC
- try to tie the notes: NUM-plus or click the "add tie" symbol

the debugger tells me, that in edit.cpp:905 (Score::cmdAddTie()), where it says
if (n->pitch() == note->pitch()) {
the pitch of the eighth note ("n") is 66 and the one of the dotted quarter note ("note") is 67, so it somehow doesn't interpret the b.

I'll file a new bug report about this issue with a link to this br, meanwhile, the workaround described above should do it.

I can't reproduce this bug. I did the following:

1. select rest after last note
2. create dotted quarter Gb as above: "n" NUM-5 NUM-dot "g" NUM-minus
3. select previous note: CUR-left
4. exit note entry mode: ESC
5. try to tie the notes: NUM-plus or click the "add tie" symbol

And I end up with two tied Gb.

Styx993, could you try with the latest nightly build?

I can't reproduce this in 1.2 or the nightly. Given the comments, I am not convinced it ever was a bug - most likely just a user misunderstanding.