My idea is that the window that contains the simulation gets bigger, but the actual simulation area stays the same. This would mean that there is a border around the simulation area. Here are some of my ideas for using this space:

1) Along the top could be the console, so you can always have it open.
2) Even above that, on the very top, is the HUD that always seems to be in the way.
3) The left side would have a slider/indicator for gravity strength, and perhaps a little directional thing to show what direction it goes (in the center would be the current radial setting, the right would cause the gravity to pull things to the right, etc.) This would allow the 'W' key to be always used for STK2.
4) Below the gravity settings would be the display settings which indicate and allow you to change the display mode without using the keys.
5) Below even that would be the same, but for the air settings.
6) On the bottom would be the stickman stats. This includes a setting which you can change the stickman control keys, life, type, and a button that would allow you to change the spawn spot.
7) In the lower right corner is a single button with the powder toy logo on it. This is the menu. If you click on it, it expands to the left, over the stickman stats, while the rest of the screen goes darker. the grouping is not important to me, but if there is a group within a group, you just hover the mouse over the group and it will expand. The following goes for all menus, submenus, etc. : clicking will open it so that you have to click to get it to close, but hovering over it will open it so that it will close whenever the mouse cursor leaves the menu. When you hover the mouse over an element, the very top of the screen shows what properties the element has.
8) In the lower left corner, there is a button which will open up a menu with all of the elements on the same page. This menu can be used to select the current element for the mouse buttons, but also tells you what categories the element can be found in the other menu.
9) If you press a key while you right click on an element in the menu(s), it will connect that element to that key, so that when you press the key, that will be the element for the right mouse. The same goes for left click, but you left click when you click the element with the selected key down.
10) The farthest top that is not taken by the console on the right side has two small boxes side by side that can be used to edit properties of the elements of the left and right click elements as well as the shape and size of the pen.
11) All of the complex keyboard shortcuts have a simple button on the left side, underneath the air settings (copy, save, rectangle etc.).
12) If you ALT+click a particle, it selects it. A box pops up that has the settings such as temperature, pressure, and the like.
13) The zoom window is always there, along with a directional toggle switch that controls where it is, but it is underneath the right/left element settings.
14) The bar along the bottom is the same, but it has an additional button for the stamps panel.
15) When you click on the button to download a saved creation or access stamps, a panel that covers only the side if the screen that the button is on, but does not cover the simulation area. (Left for downloading, right for stamps.)
16) There is a button/indicator that changes the size of the simulation area. The size of the particles stays the same, but you can scroll around the area by pressing CTRL while dragging the mouse. I know that this idea is not very stable, but I think that it can be done, and it doesn't have to go very big.

I was kind of planning on doing maybe 4 or 5 ideas, but they just kept popping up in my head. I will be very happy if I see any of these ideas in any future versions of the powder toy.

P.S. I like the current theme of black with white borders/text, so don't change it please.


More Ideas coming into the station now...
17) In the element properties/settings (includes the ALT+click and the left/right element settings) you can also set channels for WIFI, portals and whatever else may use channels.
18) A button somewhere that toggles a barrier around the simulation area. Maybe you can choose what element/wall is used?
19) Along the far right side is a bar about the thickness of 6 characters. This contains the 20-ish most recent elements/walls used. It may just show the name, symbol, or color, or it may have any combination of the three.
20) A slider that could control the speed of the simulation. Maybe not to make it go faster, but to make it go in slow motion for perhaps a higher frame-rate for the same distance a particle moves, making the simulation more accurate.
20.5) A record button, so you can record a reaction that may take a while, then play it back faster with an extremely high frame-rate, because it would record frame-by-frame and play it back faster. Then we could share our recorded playback as well as our creations. This way, you could start a simulation of the whole screen filled with an atomic bomb, hit record, go to work/school/shopping/wherever else you need to go, and when you get back, hit stop, play, and relax as the bomb goes off with no lag at 35 fps.

@Neospector
If you kept the size of the simulation area the same, or even decreased it with idea number 16, the only parts that would need to be redrawn each frame would be the HUD and the simulation area, which are already on the current version.