One item per line. Put @ then the quarter(s) it spans:

Onboarding redesign @ Q2-Q3
Billing v2 @ Q2
Mobile app @ Q3-Q4

Start a line with # to open a new swimlane:

# Build
Search revamp @ Q1-Q2

Spans accept quarter keys (Q1-Q3), column numbers (1-3), or a single box (Q2). Rename the boxes under Timeboxes.

Or edit on the chart: drag a bar to move it (between lanes too), drag its edges to resize, double-click to rename, and hover for delete. Drag across empty space to draw a new bar.

Lanes: double-click a lane name to rename, drag its grip to reorder, hover to delete, or use “+ Add lane” under the chart.

Undo anything with ⌘Z / Ctrl-Z. Set the palette, dark mode, and export background under Style.