Cursor & Selection

A cursor: a position in the buffer.

A selection: a range (start, end). Cursor is at one end (the "active" end).

Movement:

• Left/right arrow: pos -= 1 / += 1, clear selection_start.
• Shift+arrow: pos -= 1 / += 1, KEEP selection_start.
• Ctrl+arrow: word boundaries.
• Home/End: line start/end.
• Page up/down: viewport-sized jumps.

Multi-cursor:

• Multiple Cursor instances simultaneously.
• Each tracks its own pos + selection.
• Edits applied to all simultaneously.
• Sublime Text popularized.
• Implementation: list of cursors; sort by pos for edit application.

Visual modes (Vim):

• Character mode: select by character.
• Line mode: select whole lines.
• Block mode: rectangular column selection.
• Different operations apply differently.

Cursor blink:

• Visual feedback.
• Toggle every 500ms when idle.
• Stop blinking during edit (looks better).

Mouse interaction:

• Click: place cursor.
• Click + drag: select range.
• Double-click: select word.
• Triple-click: select line.
• Shift+click: extend selection.
• Ctrl+click: add cursor (multi-cursor).

Word boundaries:

• Default: alphanumeric vs non-alphanumeric.
• Cursor jumps to next word boundary.
• Configurable (camelCase splitting, etc.).

Bracket matching:

• When cursor on (, highlight matching ).
• Stack-based scan from cursor.
• Editor extension feature.