Hi Panagiotis,
Thanks for the feedback!
That vertical icon bar on the far left is new in 5.2. It was key to allowing us to free up more space - moving the Debug + Log screens to their own pane. (i.e. now the screen is only ever split vertically in 2 - instead of sometimes split into 4 pains - 2 verticle and 2 horizontal).
The font scale and tab size options were there before too - but are somewhat more discoverable now that we have that cog wheel.
Glad you like the changes!