Signatures render into the main document - the identity form's live preview
and the composer's signature block - rather than the sandboxed iframe used for
message bodies. SIGNATURE_SANITIZE_CONFIG allows no target attribute, so those
anchors were live and target-less: one click navigated the whole app away,
discarding the unsent draft or the unsaved signature with it.
Add sanitizeSignatureHtmlForDisplay, which keeps the storage sanitizer's image
restrictions but forces target="_blank" rel="noopener noreferrer" on every
anchor, and use it at the two render sites. The composer's SignatureBlock
NodeView stamps the target on its rendered DOM instead, because attrs.html is
what serializeEditorContent emits into the sent message - storage and the
recipient's copy stay exactly as the user wrote them.
Plain-text bodies render into the main document rather than the sandboxed
iframe, so an anchor without target="_blank" navigates the whole app away
instead of opening a new tab.
plainTextToSafeHtml emits target and rel correctly, but
sanitizePlainTextRenderedHtml stripped both back off: DOMPurify URI-tests
every attribute value not on its URI-safe list, and "_blank" does not match
PLAIN_TEXT_RENDERED_CONFIG's ALLOWED_URI_REGEXP. EMAIL_SANITIZE_CONFIG avoids
this only because its regex carries a catch-all alternation for non-URI values.
Mark target and rel as URI-safe so they survive the URI test, rather than
loosening href validation.
Message-list rows are tinted with the first tag's color, which becomes
overwhelming when a label applies to most messages (for example
per-account labels). Add a `tintListRowsByTag` setting (default true, so
current behavior is unchanged) with a toggle in Settings beside
"Colorful Sidebar Icons". When off, rows are not tinted; tag dots and
chips still show the color. Gated in both list renderers
(email-list-item and thread-list-item).
