The Edit|Copy as HTML menu item is a toggle switch. Selecting the menu item toggles the switch and also immediately invokes Edit|Copy so that the contents of the clipboard immediately reflect the state of the switch. Turning on Edit|Copy as HTML does not turn off Edit|Copy as RTF. Both can be active at the same time.
When Edit|Copy as HTML is checked, Edit|Cut and Edit|Copy make the cut or copied text available in HTML format on the clipboard in addition to EditPad Pro’s usual clipboard formats. Edit|Cut Append and Edit|Copy Append can append to the HTML already on the clipboard if it was put there by EditPad Pro.
The HTML or RTF that EditPad Pro places on the clipboard is the same text that you selected in EditPad Pro with added HTML or RTF tags that apply the same font and colors to the text as you see in EditPad Pro. When you paste into a web editor or a word processor that understands the HTML or RTF clipboard format, the pasted text will have (almost) the same appearance in your web editor or word processor as it had in EditPad Pro. That includes any highlighting such as search matches or misspelled words. You may want to turn off Extra|Live Spelling before pasting into an important document. Double-click actions like opening URLs are not added to the HTML or RTF.
The copied text uses the same colors as you’re using in EditPad, including any background colors. If you want to paste into a document that will be printed on white paper, you may want to switch EditPad to one of its color palettes designed for printing. If you want to paste into a website that uses a dark theme, you may want to switch EditPad to a dark palette first.
EditPad always makes the text available on the clipboard as unformatted text. Applications such as Notepad (and even EditPad itself) that can only paste unformatted text will paste that unformatted text even if EditPad also made HTML or RTF available on the clipboard. You can use Block|Export to HTML or RTF and then open the exported file if you want to use EditPad to look at the HTML or RTF that EditPad generates.
HTML and/or RTF are offered as an additional format. The HTML or RTF is only generated when another application requests it. When copying and pasting within EditPad or between EditPad and another plain text editor, no time or memory is wasted to generate the HTML or RTF. If you like syntax coloring to be preserved when pasting into word processors then you can leave this option turned on permanently. You only need to turn it off if you want to paste unformatted text into an application that would prefer to paste the HTML or RTF.
Some applications can paste only HTML or RTF. Microsoft Excel, for example, can paste HTML but not RTF. So you may need to tick both Edit|Copy as HTML and Edit|Copy as RTF to be able to paste formatted text in all your applications.
Some applications can paste both HTML and RTF, but support one format better than the other. In that case you may want to tick only one of the two formats to see which gives better results when pasting. Microsoft Word, for example, supports both formats. But it interprets some background colors differently depending on the format.
Edit|Copy as RTF
Block|Export to HTML or RTF