Text Highlight, Underline and Strikeout

Mark the sheet's own text by sweeping across it, the way you would in a document.

Three tools mark text the document already has, rather than drawing on the page. They are the same tool in three costumes: the same sweep, the same selection, the same stored geometry. Only the mark drawn over the selection differs.

Use them: arm the tool and drag across the text. The cursor is an I-beam, and the selection follows the text runs on the page rather than a rectangle you drag, so a sweep across two lines marks both lines rather than the block between them.

The three

Tool	Default	Size control	Opacity
Text Highlight	Translucent yellow	None. The band is the height of the text it covers.	Yes
Underline	Red, weight 1	Weight, 1 to 10	No
Strikeout	Red, weight 1	Weight, 1 to 10	No

Underline and Strikeout are solid on purpose: they are marks on text, not washes over it.

Notes

These only work where the sheet has a text layer to select. A scanned drawing is a picture of text, not text, so nothing selects and nothing marks. For a scan, the Highlighter draws a band over the area regardless of what is underneath.
Each saves as the standard PDF annotation of the same name, so in another viewer a highlight is still a highlight, attached to the text it was drawn on rather than to a position on the page. Ink drawn over the same words would arrive as a shape that happens to sit near them.