Clipboard
clipboard feature is used to enable system clipboard read/write capability. It is suitable for implementing copy, paste, import/export of temporary text and similar functionality.
Basic Usage
Clipboard entry is in platform layer. When using import ClipboardApi trait, then create Clipboard.
Clipboard(None) means not binding specific window. When you need to associate clipboard operation with a given window, can pass Some(window_id).
Supported Content
ClipboardApi provides two kinds of entries:
Common clipboard formats are represented by ClipboardType, including Text, Image, Rtf, Html, Files. If want to exchange complex data with other applications, can first register custom format, then read/write corresponding bytes.

