I VERY OFTEN unable to select the dialogue I want, when talking to an npc. The mouse pointer highlights the sentence I want to say, but when I click the mouse button--or hit enter--it automatically switches to a dialogue option further up in the list.

Is this a known bug that you are working on?

Happens also to me quite often. Not that bad a problem with most of the dialogues, but sometimes this causes unnecessary need to reload an earlier save.

Not only in dialogues, also stuff like reloading savegames. The whole interface is borked

Same here. Even the larger text like "WEAPONS / APPAREL / MISC" etc only seem to work about 50% of the time. Also, the default behavior of the interface seems to be to exit when you click on an empty space (despite my clicking directly on the text). So, I have to talk to the character AGAIN and try to find the dialogue (which I may or may not be able to select AGAIN).

This is a real pain. I'm betting this something inherited from the console interface. I'm further betting that this problem would go away if you could pick a console screen resolution on the PC.