Tree Viewer button to jump to ErrorNode or ruleFailedAndMatchedNothing

[yaccoff]

First off really great tool this, liking it lots. I am using the tool to parser a very old obscure programming language and its finding lots of syntax issues, which result in the Jave code catching the exception and print the error line and number. However, I find that in some cases the error isnt actually on that line but on an adjacent line. But thats not the point of my suggestion.

As well as finding errors by line numbers programmatically, I am using the Tree Viewer quite a lot to ensure that the code has been correctly processed by the grammer. Given that some of the files have 10K of code in them, this entails quite a lot of scrolling.

I wanted to suggest that we add another 'Error' button to the TreeViewer, which would jump/scroll the view to show the offending 'LIGHT_RED' highlighted node.