M7: the Edit text caret is as tall as the row it is on (#2462)

In a region that mixes sizes (a 24 pt title over 12 pt lines), the
inline editor's caret on a small row was as tall as the region's first
size and reached into the row below. egui draws the caret at least one
row of the TextEdit's font tall, and that font had the paragraph's first
size. Each row already carries its source row's height, so the
TextEdit's font is now half the region's smallest size and only sets
that floor.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>

parity/acrobat-features.toml

@@ -1866,7 +1866,7 @@ milestone = "M7"
 status = "partial"
 commands = ["edit.edit_text"]
 tools = ["text_lines", "text_paragraphs", "text_edit", "text_edit_layout", "text_font_files", "text_font_import", "text_fonts"]
-evidence = ["crates/edit/src/tests.rs::paragraphs_are_found_and_rewrapped", "crates/edit/src/tests.rs::text_lines_are_found_and_replaced_in_place", "crates/ui-egui/tests/editing.rs::editing_existing_text_in_place", "crates/automation/tests/automation.rs::editing_existing_text_through_tools", "crates/edit/src/tests.rs::a_line_whose_operator_starts_the_next_stream_can_be_edited", "crates/automation/tests/automation.rs::a_line_split_across_content_streams_is_listed_and_edited", "crates/ui-egui/tests/editing.rs::selected_text_formatting_keeps_the_rest_of_the_paragraph_and_reopens", "crates/edit/src/tests.rs::marked_paragraph_boundaries_and_cross_stream_transforms_survive_rewrite", "crates/automation/tests/automation.rs::explicit_font_and_disjoint_ranges_save_reopen_through_tools", "crates/edit/src/tests.rs::disjoint_style_ranges_preserve_unselected_runs_and_validate_utf8_atomically", "crates/engine/tests/document_fonts.rs::opentype_cff_document_font_preserves_program_codes_and_rendering_after_reopen", "crates/ui-egui/tests/editing.rs::cropped_images_do_not_intercept_text_and_stay_inside_each_page", "crates/automation/tests/automation.rs::clipped_image_bounds_and_text_edit_save_reopen_through_tools", "crates/edit/src/tests.rs::mixed_styles_and_matrix_sizes_form_visual_regions_without_merging_columns", "crates/edit/src/tests.rs::rich_region_edits_preserve_styles_positions_and_delete_all_runs_after_reopen", "crates/ui-egui/tests/editing.rs::one_editor_contains_mixed_styles_and_visual_rows", "crates/ui-egui/tests/editing.rs::inline_editor_preserves_source_font_and_previews_live_bounds", "crates/fonts/src/pdf.rs::mac_subset_cmap_uses_pdf_unicode_without_changing_source_program", "crates/automation/tests/automation.rs::mixed_visual_region_edit_preview_save_reopen_and_undo_through_tools", "crates/ui-egui/tests/ui.rs::the_edit_tab_turns_on_edit_text_and_images"]
+evidence = ["crates/edit/src/tests.rs::paragraphs_are_found_and_rewrapped", "crates/edit/src/tests.rs::text_lines_are_found_and_replaced_in_place", "crates/ui-egui/tests/editing.rs::editing_existing_text_in_place", "crates/automation/tests/automation.rs::editing_existing_text_through_tools", "crates/edit/src/tests.rs::a_line_whose_operator_starts_the_next_stream_can_be_edited", "crates/automation/tests/automation.rs::a_line_split_across_content_streams_is_listed_and_edited", "crates/ui-egui/tests/editing.rs::selected_text_formatting_keeps_the_rest_of_the_paragraph_and_reopens", "crates/edit/src/tests.rs::marked_paragraph_boundaries_and_cross_stream_transforms_survive_rewrite", "crates/automation/tests/automation.rs::explicit_font_and_disjoint_ranges_save_reopen_through_tools", "crates/edit/src/tests.rs::disjoint_style_ranges_preserve_unselected_runs_and_validate_utf8_atomically", "crates/engine/tests/document_fonts.rs::opentype_cff_document_font_preserves_program_codes_and_rendering_after_reopen", "crates/ui-egui/tests/editing.rs::cropped_images_do_not_intercept_text_and_stay_inside_each_page", "crates/automation/tests/automation.rs::clipped_image_bounds_and_text_edit_save_reopen_through_tools", "crates/edit/src/tests.rs::mixed_styles_and_matrix_sizes_form_visual_regions_without_merging_columns", "crates/edit/src/tests.rs::rich_region_edits_preserve_styles_positions_and_delete_all_runs_after_reopen", "crates/ui-egui/tests/editing.rs::one_editor_contains_mixed_styles_and_visual_rows", "crates/ui-egui/tests/editing.rs::inline_editor_preserves_source_font_and_previews_live_bounds", "crates/fonts/src/pdf.rs::mac_subset_cmap_uses_pdf_unicode_without_changing_source_program", "crates/automation/tests/automation.rs::mixed_visual_region_edit_preview_save_reopen_and_undo_through_tools", "crates/ui-egui/tests/ui.rs::the_edit_tab_turns_on_edit_text_and_images", "crates/ui-egui/tests/editing.rs::the_caret_on_a_small_row_is_as_tall_as_that_row"]
 notes = "The Edit tab turns Edit text & images on at once, as in Acrobat (leaving the tab puts the tool down and applies an edit in progress); click a paragraph box and retype it in place (font reused or Helvetica substituted, colour and spacing kept, rewrapped); a page's /Contents pieces are parsed joined, so a line whose operands and operator sit in different pieces is listed and edited (lines and paragraphs still don't join across pieces; Edit image still parses each piece alone); drag a box to move it or its right-edge handle to rewrap it (edit.text-move-resize); per-character formatting changes are next Since #1116: mixed-style visual regions retain source rows, subset encodings, colour and baseline anchors in one textless-background editor. Explicit paragraph/heading scopes constrain grouping; compatible graphics planes permit cross-stream regions. Full matching document fonts complete absent subset glyphs; installed/file selection, TrueType/OpenType-CFF embedding and disjoint UTF-8 range styles have save/reopen coverage. Single-face OpenType shaping/bidi retains logical text through ToUnicode/ActualText. Legacy non-SFNT preview, mixed-font/style contextual runs, full structure-tree preservation and author intent in untagged PDFs remain limited; see docs/editing-existing-text.md"
 
 [[feature]]