In file "testlink\third_party\fckeditor\editor\css\fck_editorarea.css" I found this comment:
/*
Just uncomment the following block if you want to avoid spaces between paragraphs. Remember to apply the same style in your output front end page.
*/
I have uncommented that block and now I don't have spaces between paragraphs when I edit summary/steps/exp. result of test case on Specification page. I like it very much.
But on Execution page there are spaces between paragraphs in the text of summary/steps/exp. results. I tried to change "testlink\gui\themes\theme_m1\css\testlink.css" file but did not get result.
It is necessary to copy uncommented block from "testlink\third_party\fckeditor\editor\css\fck_editorarea.css" to "c:\xampp\htdocs\testlink\gui\themes\theme_m1\css\testlink.css".