This popup is there for text file manipulating. You also show it using as context menu by holding shift and pressing right mouse button...
Set font
Set font color
Font attributes - popup
Align left
Align center
Align right
Increase indent
Decrease indent
Find
Find next
Replace
Word wrap
Selection - popup

Set font - shows dialog box, in which you can select font for selected text block. If no text's selected, program set's current font...
Set font color - selects color of text font (check previous paragraph for rules about selection)
Font attributes - using items in this popup can you set attributes of selected block or actual font. I hope, that it will be easy to use these commands without help too. If you use item 'Read-only', I warn you - it may not work in text editors (but text won't be damaged). To disable any attribute from group [Bold, Italic, Underlined, Read-only], just use the same command 2nd time...
Align left - aligns actual line (if more lines of text are selected, the it aligns all lines) left
Align center - aligns actual line (if more lines of text are selected, the it aligns all lines) center
Aling right - aligns actual line (if more lines of text are selected, the it aligns all lines) right
Increase indent - increses indent of actual line(if more lines of text are selected, the it indents all lines)
Decrease indent - decreases indent of actual line (if more lines of text are selected, the it indents all lines)
Find - finds selected text using selected criteria
Find next - finds next occur of text in document
Replace - replaces selected text to other
Word wrap - wraps text so it will fit into window / cancels wrapping
Selection - sets style of selection (words/letters)