UE2:UnrealEd viewport

The viewport is a floating/docked window that renders the current world, there are four kind of viewports Top, Front, Side and Perspective, which all have a toolbar with options of how to render the world.

Toolbar

Buttons from left to right with keyboard shortcut, if any:

Realtime Preview (P) 

When enabled the viewport will update all actors like in-game e.g. Emitters, Sounds, Fog, Animations will all be updated every tick.

Top (Alt+7) 

Set this viewport to top (X/Y only) wireframe view.

Front (Alt+8) 

Set this viewport to front (X/Z only) wireframe view.

Side (Alt+9) 

Set this viewport to side (Y/Z only) wireframe view.

Perspective (Alt+1) 

Set this viewport to perspective wireframe view.

Texture Usage (Alt+3) 

Set this viewport to perspective unlit texture usage view. Each BSP surface's texture is replaced with a distinct solid color.

BSP Cuts (Alt+4) 

Set this viewport to perspective unlit BSP cuts view.

Textured (Alt+6) 

Set this viewport to perspective unlit textured view. Textures are drawn as seen in-game, but no lighting is applied.

Lighting Only (Alt+0) 

Set this viewport to perspective lighting-only view. All BSP surfaces, meshes and mesh-like objects are rendered with a white texture to which the lighting is applied.

Dynamic Light (Alt+5) 

Set this viewport to perspective lit textured view. Textures and lighting is drawn as seen in-game.

Zone/Portal (Alt+2) 

Set this viewport to perspective unlit zone view. Each zone's BSP polygons are assigned different shades of a base color that is picked per zone. This view lets you see actual polygons created by BSP cuts.

Depth Complexity 

Set this viewport to perspective depth complexity view. In this mode, overdraw is visualized by causing overlapping rendered objects to go more towards red, while non-overlapping objects are rendered in green. Use this in combination with realtime preview mode to find areas with heavy overdraw. Overdraw generally degrades performance, so you will usually want to optimize the affected areas.

Lock to Selected Actor? 

Locks the camera to the selected actor. Moving the camera actually updates the selected actor's location and rotation.

Show Large Vertices? 

Increases the size of the selected brush's/volume's vertices.

Shortcuts

The unreal editor provides many shortcuts to complete tasks faster. Here's a list of Mouse and Keyboard shortcuts related to the viewport.

Mouse

Shortcuts that require input from a mouse.

A
LeftButton
Release - Add actor here
L
LeftButton
Release - Add light here
LeftButton
Hold - Rotate camera left/right, move camera forward/backward
Release - Select actor/surface
RightButton
Hold - Move camera left/right, move camera up/down
MiddleButton
Hold - Draw a meter measure line
RightButton
Hold - Rotate camera left/right, rotate camera up/down
Release - Open context menu
Ctrl
LeftButton
Hold - Move all selected surfaces left/right, Move all selected actors in direction X
RightButton
Hold - Move all selected actors in direction up/down, Scale all selected surfaces(forward to scale up, backward to scale down)
RightButton
Hold - Move all selected surfaces up/down, Move all selected actors in direction Y
Alt
Hold - Make a square selection
Alt
LeftButton
Release - Apply texture to selected surface
RightButton
Release - Copy texture from selected surface
Hold - Move camera roll

Keyboard

Shortcuts that require input from a keyboard.

F4 - Show the Object Properties window
F5 - Show the Surface Properties window
F6 - Show the Level Properties window
F7 - Recompile scripts
F8 - Show the Build Options window
Delete - Delete all selected actors
P - Toggle realtime preview
Visibility
B - Show/Hide active Brush
E - Show/Hide event lines
F - Show/Hide Fog
K - Show/Hide backdrop
O - Show/Hide Volumes
S - Show/Hide selection highlight
T - Show/Hide Terrain
W - Show/Hide StaticMeshes
Shift
Surface
B - Select all surfaces from current selected brush
C - Select all adjacent coplanar surfaces
D - Deselect all surfaces
F - Select all adjacent floor surfaces
G - Select all surfaces matching the current selected surface group
I - Select all surfaces matching the current selected surface items
J - Select all adjacent surfaces
M - Memorize all selected surfaces
N - Deselect all surfaces
O - Add all memorized surfaces to selection
Q - Reverse:Select all unselected surfaces and deselect all selected surfaces
R - Deselect all and select all memorized surfaces
S - Select all adjacent slants
T - Select all surfaces matching the current selected surface texture
U - Deselect all surfaces that are not memorized and select all memorized surfaces
W - Select all adjacent wall surfaces
X - Deselect all memorized selected surfaces and select all memorized surfaces that were not selected
Z - Select nothing (Broken?)
Actor
A - Select all actors
D - Duplicate all actors
Ctrl
A - Executes the Add toolbar button
B - Open brush (Broken?)
C - Copies all selected actors/text
D - Executes the deintersect toolbar button
E - Save map as
L - Save map
O - Load map
P - Play map
I - Executes the Intersect toolbar button
S - Executes the Subtract toolbar button
V - Paste the data from clipboard
W - Duplicate all selected actors
X - Cut all selected actors/text
Y - Redo last action
Z - Undo last action