Feature request: Single‐slot captions (replace old caption instead of stacking)

Context and Problem

When using Gource with caption animations (--seconds-per-day 0.05, --caption-duration 1.0), multiple captions can overlap and stack vertically.

Wiki reference: https://github.com/acaudwell/Gource/wiki/Captions

Desired Behavior

Gource should support a single-slot captions mode where any new caption replaces the currently displayed caption if it is still visible, ensuring at most one caption is shown at any time.

Steps to Reproduce

1. Generate a log with multiple caption events close together.

2. Run:

   bash复制

   gource --seconds-per-day 0.05 \
          --caption-file captions.csv \
          --caption-duration 1.0 \
          --caption-offset 0 \
          path/to/repo

3. Observe that captions stack when intervals overlap.

Proposed Solution

• Add a new option, e.g. --single-slot-captions, that enforces rollover behavior.

Bounty

I am offering a US$200 bounty (preferably paid in Bitcoin). Open to alternative payment methods—please discuss before claim.

Thank you for considering this enhancement!