HTML Text Editor dialog box should be used to apply rich text formatting to the plot axis titles, series text, labels and worksheet column captions. Rich text implementation based on a small subset of HTML tags, so you use this tool to insert HTML tags and symbols (according to HTML standards, such symbols as Greek letters and mathematical signs are represented by so-called named entities). Following features are supported:
Tags: bold, italic, underline, subscript and superscript
α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ σ τ υ φ χ ψ ω
Α Β Γ Δ Ε Ζ Η Θ Ι Κ Λ Μ Ν Ξ Ο Π Ρ Σ Τ Υ Φ Χ Ψ Ω
In the object properties dialog box, click the button with [</>] image as shown on the screenshot.
You will see small dialog box with a toolbar and two panes. Top pane is the text editor. To make characters bold, italic, underline, subscript or superscript, select text in this editor and click appropriate toolbar button. To insert a symbol, select it from the drop-down list and click [Ω] button. You can click this button several times to insert several copies of selected symbol into different places of your text. After you finish editing, click Ok button to save changes or Cancel button to discard changes.
Bottom pane is a "preview" area. Font and color of this area initialized according to the properties of an object whose text is to be edited.