When you select an object on the Canvas, the inspector sidebar switches over to the Object inspector automatically. From there, you can use the inspectors to change anything about the selected object.

To select several objects at once, click in an empty area of the canvas and drag a box around the objects. If you hold Option, only objects entirely inside the rectangle are selected. You can also Command- or Shift-click an object to add it to or remove it from the selection.

To select a member of a group, table, or subgraph, click once to select the group as a whole, then click again to select the member. The rest of the canvas dims to show that you are in group editing mode. Click anywhere outside the group to leave group editing mode.

If you’re using a Mac with a touch-sensitive trackpad, you can use the rotate gesture with two fingers to rotate the selected objects (be sure that Multi-Touch gestures are enabled in OmniGraffle ▸ Preferences ▸ General ▸ Multi-Touch).

To move the selected object very precisely, press the Arrow keys. Hold Option or Shift to move by larger steps.

With Smart Guides enabled (Arrange ▸ Guides ▸ Smart Alignment Guides and Smart Distance Guides), you can line up objects and space them on the Canvas precisely. Hold Command after you start dragging to temporarily enable or disable Smart Guides.

To drag a copy of an object instead of the object itself, hold Option as you drag.

To change the shape’s size, use the Selection tool to click and drag one of the resize controls. As you click and drag on one of the handles, you’ll notice that the object is anchored by the opposing handle, and the object resizes in the direction you are moving the mouse.

The following keys provide additional functionality when interacting with the resizing handles:

• Hold Shift while resizing to maintain the aspect ratio of the original object.
• Hold Option to resize an object with its center point being anchored.
• Hold Shift-Option while resizing to maintain the aspect ratio and resize the object based on its center point.
• Hold Command, and the resize control changes to a rotate control so you can rotate the object.

If you have objects of different sizes on the canvas, but would like them to be the same size, first select the object that has the dimensions you'd like the others to emulate, choose Arrange ▸ Size and then choose one of the resizing options.

If you select a table, the edge handles look like little grids. You can drag them to change the number of rows or columns in the table. Drag the corner handles to resize the table normally.

Any line (created with the Line tool) has two points: a red one at its source and a green one at its destination. A line may also pass through any number of blue midpoints. Drag one of the points to move it; by dragging the source or destination point you can make the line connect to or disconnect from other objects.

Custom shapes (created with the Pen tool) and Bézier-type lines have control points at each vertex. Click a control point to select it; if a control point is hiding behind a selection handle, Option-Command-click to select it, or just select a different control point first to make the handles go away. If a control point has Bézier handles, they appear when you select the point:

• Drag either of the two handles to adjust both, or Option-drag to adjust them one at a time.
• Shift-drag to constrain the handle’s angle to 45-degree increments.
• Command-drag a point to give it handles.
• If you drag a handle close enough to the point itself, the handle disappears entirely.

The default way to add points to an existing line is to double-click the line, but this can be changed in the General preferences (OmniGraffle ▸ Preferences ▸ General).

To add a point to a custom shape, double-click somewhere along the shape’s stroke.

To delete a point from a line or a custom shape, select it and then either press the Delete key or select Edit ▸ Delete from the menu bar.

To create a shape:

• Drag across the canvas until you get the size you want.

• Hold Shift while dragging to make a shape of equal width and height (a perfect square, a perfect circle, and so on).

Once you have created a shape, you can select it and change its attributes with the Object, Type, and Properties inspectors.

To create a new line:

• Click where you would like the source of the line; this can be an object (to which the line will stay attached) or an empty spot on the canvas (so the beginning of the line remains unattached).

• Click as many empty spots on the canvas as you like to give the line midpoints.

• End the line at an object by clicking the object (to which the line will stay attached), or end the line at an empty spot on the canvas by double-clicking there; this can be changed in the Drawing Tools preferences (OmniGraffle ▸ Preferences ▸ Drawing Tools ▸ Line Editing).

Hold Shift while drawing a line to constrain the next point to angles at 45-degree increments from the previous point. Hold Option while drawing a line to prevent it from connecting to objects.

When two objects are connected by a line, the object at the source is considered the parent of the object at the destination. This defines the objects’ relationship in the outline view and when you use automatic layout.

Lines can have line labels attached to them. Click a line with the Text tool to create a new text label. Or, drag an existing blob of text to the line until the line is highlighted, then drop it to attach it as a label.

Click a shape to start editing its text. While you are in text editing mode, the top ruler becomes a text ruler, and you can use standard OS X text editing commands (for example, you can use the arrow keys to move the insertion point around).

Click or drag in an empty area of the canvas to create a new shape with settings particularly suited to containing text. A single click creates an object that expands horizontally to fit the text you enter; a drag creates an object of a specific width. Remember that the objects you create in this way are not fundamentally different from other shapes; they just start with certain settings in the Text inspector which make them convenient for containing text.

Click a connection line to add a new label to it. This label is just like the object created when you click an empty area of the canvas, except it is attached as a line label.

Text inside objects can be found by OS X’s Spotlight search feature, in case you need to find your OmniGraffle diagrams that contain certain words.

To start a new shape, click anywhere on the canvas. Each subsequent click adds a new point to the shape, until you double-click or press Return to make the final point. At any step along the way, instead of just clicking, click and drag to create a point with Bézier handles. While creating a shape, you can press Delete to remove the last point you added.

Bézier handles can define any shape, once you get the hang of them. Each point can have a handle facing the next point, and a handle facing the previous point. The line between two points is defined by the first point’s forward-facing handle and the second point’s backward-facing handle. With no handles at all, you get a perfectly straight line. With handles, the line between them is a curve that tries to compromise between the handles’ length and direction. This is truly one of those things that makes a ton more sense once you try it for yourself, so please do.

Once you have created a shape, you can select it with the Selection tool and edit its points, adjust existing handles, add handles to points without them, or change the shape’s attributes with the Object, Type, and Properties inspectors.

You can move the divider in the Drawing Tools preferences to change which tools are available in the palette’s collapsed state, or get rid of the Expando-Collapso button entirely.

With nothing selected, click any empty spot on the Canvas to create a new generic shape there and select it. Once you have a shape selected, try some of these combinations:

• Click any empty spot on the canvas to create a new shape connected to the original one.
• Hold Option to create a sibling (connected to the same parent as the selected shape) instead.
• Hold Shift to add an aunt (essentially reversing the connection line of the new object).
• Hold Command to create a completely disconnected shape.

If you already have an object on the Canvas, first select it with the Selection Tool so that you can use it as a starting point for creating more connected shapes, and then switch to the Diagram Tool by pressing and holding the d key.

Once you get the hang of the modifier keys, you can create really complex diagrams with just a few clicks.

The tool’s popup menu contains a list of styles that can be absorbed; select whichever ones you like, and the brush will only absorb or apply those styles. For example, if you only select Fill, you can apply a certain fill style to objects without affecting any of their other styles.

To reset the contents of the brush, select Clear Contents from the Brush tool’s popup menu; you can then absorb a new style. You can also Option-click a different object to replace the brush’s contents.

If you hold the Shift key down, the Rubber Stamp tool will align the soon-to-be-pasted object along the centerline (either horizontally or vertically) of the original or previously pasted copy.

To reset the contents of the stamp, select Clear Contents from the tool’s popup menu; you can then grab a new object. You can also Option-click a different object to replace the stamp’s contents.

Magnets are special spots on a shape that attract connection lines. If there are no magnets on a shape, all lines connect to the shape’s center by default. If there is at least one magnet, each connected line is attracted to the nearest one. You can also connect lines directly to magnets, to make sure they stay connected to the same magnet regardless of how the shape is moved.

You can view the magnet presets in the Connections inspector (Command–3). However, if you want to place magnets in very specific places on a shape, click the Magnet Tool and then click anywhere on the object.

To change a magnet’s position on the object, click and drag an existing magnet to another location. If an object has more than one magnet, Smart Guides will appear so you can align the magnets as well. To delete a magnet, Shift- or Option-click on a magnet.

Click and drag a box across the canvas to specify the rectangle you would like to zoom to; the shading shows the area that will be visible in the window when you let go. If you Option-drag, the rectangle is centered on the spot where you start dragging. While dragging, press and hold Shift to move the zoom selection area around instead of resizing it.

Shift-click the zoom tool in the tool palette to return to 100 percent zoom, or actual size.

You can always zoom to a specific percentage with the zoom menu in the lower-right of the canvas window.

If your Mac has a Multi-Touch–capable trackpad, you can use it to change the zoom level using the pinch gesture. To enable Multi-Touch, go to OmniGraffle ▸ Preferences ▸ General ▸ Multi-Touch and turn on Enable Multi-Touch trackpad gestures. Now you can pinch open to zoom in, or pinch close to zoom out. Multi-Touch zoom makes it much easier for you to zoom-in and -out on the objects on the Canvas.

You’ll mostly use the Hand tool when you’re zoomed in on the canvas and want to move to a different location. For this, use the Hand tool’s quick access key, the Space Bar, to switch the mouse pointer to a hand, and then click and drag to move the canvas around.

As you drag, you’ll notice that the open hand changes to a clutched fist to indicate that you’re grabbing onto the Canvas.

The secret here is that you assign actions to objects using the Action properties inspector (Command–3), which is only available in OmniGraffle Pro. First create and select an object on the Canvas, then switch to the Action properties inspector. By default, an object Does Nothing, which means it just sits there on the canvas looking pretty. Other Actions you can bind to an object include:

• Opens a URL — lets you assign a URL to open; when clicked, the page opens in the user’s default web browser.
• Opens a File — lets you assign a file to open; when clicked, the file opens in the default app based on that file type’s preferences. You can also choose to open a synchronized file in an OmniPresence folder.
• Runs a Script — runs an AppleScript when the object is clicked.
• Jumps Elsewhere — lets you jump to another Canvas in the OmniGraffle project, highlight other objects, or zoom in or out on the canvas.
• Shows or Hides Layers — lets you show or hide specific layers in your project.

The Actions you assign to an object make it easy for you to create highly interactive presentations and even UI mockups for that killer iOS app you’re designing.

For more details, see Making Objects Interactive with the Action Inspector.