Worked a bit more on the conversation editor. Line links can now be established and broken, the "l" button and the "b" button. Lines can also be moved up and down on the same level using the left and right buttons. And I also made it so that NPC responses are colored in red and links in violet.
There are also some more visual changes like icons for most of the buttons and the three main areas, the conversation list, the tree and the line editor can be resized.