The editor overlay's anchor was only clamped to the top/left edge, so an
MTEXT placed near the right/bottom of the viewport pushed the 640px panel
(and its toolbar buttons) off-screen where they were unclickable.
Both the MText editor and the single-line TEXT editor now receive the
viewport canvas size and clamp the anchor against the right/bottom edges
too, so the whole panel stays visible and usable wherever it is opened.
Fixes#52
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
6f64d8d0d9