Clear clipboard requires clipboard to be opened

[rexx-org]

As with other clipboard command, the clipboard needs to be open for them to work.

[Bill-Gray]

Seems strange to me we've not run into trouble with this before. However, "before calling EmptyClipboard, an application must open the clipboard by using the OpenClipboard function".

However, none of the demos and none of my code calls PDC_clearclipboard(). I could imagine it going through the past couple of decades unnoticed.

This code is identical to that in wincon/pdcclip.c in PDCurses, so @wmcbrine may be interested.

[GitMensch]

However, none of the demos and none of my code calls PDC_clearclipboard(). I could imagine it going through the past couple of decades unnoticed.

That calls for an adjustment in the demos, maybe with a user dialog "please copy text to your clipboard", "this was found", "I now clear the clipboard", ...