This is still not 100% clear. You say that you want some empty space in the area marked with a black box to be occupied.
1) There is no empty space inside the black box. There are 3 lines and they are occupied.
2) If you mean the space under the black box and before the line saying 'Auto-Dash', I don't think that space can be filled. It does not correspond with any configuration option. To change the whole layout of the window to eliminate that space would require extensive alterations to the script.
3) For the switch in the red box, are you saying that you want this to read something like 'Full Screen' ON/OFF
4) If that is what you want, will you be disabling the ALT+ENTER mechanism? Because otherwise you will have 2 different ways for this to be changed, and how will you ensure that if the player chooses one way, it doesn't conflict with the other way?