Helpful keystrokes:
f - move forward one event
d - move backward one event
F - more forward 10 events
D - move backward 10 events
g - move forward to next checkpoint event
s - move backward to next checkpoint event
S - move forward to first snapshot containing the search string
spacebar - replay
right arrow - move forward one event
left arrow - move backward one event
up arrow - increase font size
down arrow - decrease font size