trace-graph: Work on fixing the zooming and horizontal scrolling

For some reason zooming in too much will cause the horizontal
scrolling to get out of sync. This is probably a rounding error
or some other strange bug. This patch cleans some of the code
up and fixes parts of it. But there's still a bug to swat.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1 file changed