In editor while editing when a new line is inserted it is aligned with preceding line i.e. indentation is controlled.
However, when some text is copied (already indentated) from same editor or from some other source and pasted in editor, indentation is lost. The first line is pasted at correct place, but second line onwards the first character of line is considered as reference instead of the position where text is pasted.
To simulate this defect open the editor and open a file. Insert two line and click tab twice. Now paste some indentated text from editor or from other source.