1. A computer-implemented method comprising: receiving text to compose, the text including a plurality of paragraphs; composing the text using paragraph composition, the paragraph composition determining a layout for the lines of each paragraph according to a line break scheme that determines line breaks for the paragraph as a whole; designating one or more paragraphs of the plurality of paragraphs as having limited recomposition; receiving a modification to a line of a paragraph, the paragraph having a plurality of lines and where the modified line is subsequent to a first line in the paragraph; determining whether the paragraph of the modified line has limited recomposition; if the paragraph has limited recomposition, recomposing a portion of the paragraph using a multi-line paragraph composition process without recomposing the full paragraph; and if the paragraph does not have limited recomposition, recomposing the full paragraph, wherein the designating further comprises receiving a user input limiting recomposition for the paragraph, where the user input flags one or more particular lines in the paragraph preventing backing up the composition beyond the flagged one or more lines.
1. A computer-implemented method comprising: receiving text to compose, the text including a plurality of paragraphs; composing the text using paragraph composition, the paragraph composition determining a layout for the lines of each paragraph according to a line break scheme that determines line breaks for the paragraph as a whole; designating one or more paragraphs of the plurality of paragraphs as having limited recomposition; receiving a modification to a line of a paragraph, the paragraph having a plurality of lines and where the modified line is subsequent to a first line in the paragraph; determining whether the paragraph of the modified line has limited recomposition; if the paragraph has limited recomposition, recomposing a portion of the paragraph using a multi-line paragraph composition process without recomposing the full paragraph; and if the paragraph does not have limited recomposition, recomposing the full paragraph, wherein the designating further comprises receiving a user input limiting recomposition for the paragraph, where the user input flags one or more particular lines in the paragraph preventing backing up the composition beyond the flagged one or more lines. 8. The method of claim 1 , where multi-line composition includes determining line breaks for two or more lines of the paragraph according to a line breaking scheme that takes all the recomposed lines into account to identify an optimal layout.