The Effects panel changes the pixels of the active layer. Open it with auto_awesome Effects in the toolbar. The line at the top names the layer it acts on; pick a different layer in the Layers panel. The panel holds two cards, Transform and Outline. Only one is open at a time: opening one closes the other. Both start closed, and the editor remembers which one you left open.

Outline

Outline draws a line around every edge of the active layer's artwork, holes included. No selection is needed. Choose the settings, then click Preview: the canvas shows the outline and follows every setting as you drag it, and the button becomes Add Outline. Click it to keep the outline: it goes on a new layer, and one Undo removes it. The artwork stays the active layer, so you can preview and add another. Cancel drops the preview. Opening the card never starts a preview on its own.

While the preview shows, everything else waits until you add or cancel it (zooming and panning still work); a small notice with Add Outline and Cancel tells you why. Enter adds the outline and Esc cancels. Closing the card or the panel drops the preview without adding anything.

• This frame / All frames: outline the active frame only, or the active layer on every frame where it is visible. The preview shows the active frame.
• Size: how wide the outline is, from 1 to 10 pixels.
• Shape: how the outline turns corners; tick one of the three. Circle rounds them; Square fills them, so staircases come out solid; Diamond cuts them, keeping diagonal outlines thin, the way pixel artists usually draw them. Square and Diamond are always hard-edged. The shape applies to Sticker too. Which looks best depends on the artwork: blocky pixel art built from square steps usually looks cleanest with Square, and smooth or soft artwork with Circle.
  
• Placement: Outside draws around the artwork on a layer below it, so the artwork's soft edges blend onto the outline. Center straddles the edge and Inside draws over the artwork's own edge; both go on a layer above it.
• Opacity: how solid the outline is. It uses the active color.
• Ignore faint pixels: pixels fainter than this opacity do not count as artwork (50% to start). If pale specks show between the artwork and the outline, raise it until they are gone. Set it too high and see-through artwork, such as a glow or a flame, stops counting and loses its outline.
• Anti-aliasing (Circle only): soft outline edges, with partial pixels on curves and diagonals. The editor ticks it for you when the artwork has soft edges and leaves it off for crisp pixel art. Change it by hand and the editor keeps your choice for that layer.
• Sticker: a die-cut backing instead of a line. It fills holes and narrow gaps, rounds off notches, and sits below the artwork. Pick white as the active color for the classic sticker look. Placement is hidden while Sticker is ticked.

The Transform card holds actions that alter the active layer's geometry. It was in the Layers panel until version 1.67. The This frame / All frames switch at the top of the card chooses whether a transform changes the active frame or every frame. To scale, skew or rotate only part of a layer by dragging handles, select it and use Free Transform.

• Rotate 90° Left / Right: Click rotate_left or rotate_right to rotate the active layer.
• Custom Angle: Type an exact degree (-180° to 180°) in Rotate and choose cleanEdge (the default: clean lines for pixel art, with no new colours, as in Free Transform), Nearest (nearest neighbor: every pixel copied exactly, edges can come out jagged) or Bilinear (smooth). The 90° buttons use the same choice; a quarter turn copies the pixels exactly with any of them. Preview, Apply and Cancel appear once there is an angle to apply. After Preview, click Apply to commit or Cancel to discard before drawing is re-enabled. Everything else waits until you do (zooming and panning still work); a small notice with Apply and Cancel tells you why. Enter applies and Esc cancels.
• Flip H / V: Click flip to instantly mirror the active layer horizontally or vertically.
• Scale Layer: Input a percentage (10% to 400%) and select Lanczos (the default: smooth, for photos and soft artwork), cleanEdge (clean lines for pixel art, with no new colours) or Nearest (nearest neighbor: hard pixel edges) to resize layer pixels. With All frames, a long cleanEdge job shows its progress frame by frame in the status bar.