Line Changes and Blank Lines

The debugging of detecting line changes when pasting continues.  There are a number of scenarios that need to be handled and tested.  First is the location of where the insertion occurs, which includes at the beginning of a line, in the middle of a line, at the end of the line, and on a blank line (at both the beginning and end of the line).  Second is the contents of the text being pasted, which could include a new line at the beginning of the text, a new line at the end of the text and a number of new lines in the text.

While testing these scenarios, a number of issues were discovered when using the delete and backspace key commands when at a blank line including when there is a blank line on the next line (delete at the end of the line) and on the previous line (backspace at the beginning of the line).

In the case of a backspace at the beginning of a line when the previous line is blank, the current line was being reported as deleted, and the previous line was being set as modified (reported as changed when the cursor leaves the line).  However, if the current line hasn't been modified, the previous (blank) line only should be reported as deleted.  If the current line is modified, again the previous line should be reported as deleted and the current line should remain as modified.

In the case of a delete at the end of the line when the next line is blank, the next line was reported as being deleted and the current line was being set as modified.  However, if the current line hasn't been modified and the next line is blank, nothing was actually modified, so it should not have been set as modified.

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