Set after editing Buf or BufTextLen in Completion/History/Always callbacks.
Read-only buffer capacity in bytes including the NUL terminator.
Text byte length excluding NUL; keep below BufSize and mark edits dirty.
Cursor byte offset in Buf for Completion/History/Always callbacks.
CharFilter character in 16-bit ImWchar; replace it or set zero to reject.
Read-only callback event flag from ImGuiInputTextFlags, such as CallbackEdit.
Read-only ImGuiKey for Completion/History: Tab, UpArrow or DownArrow.
Read-only input flags originally passed to the text widget.
Selection end byte offset; equals SelectionStart when nothing is selected.
Selection start byte offset; equals SelectionEnd when nothing is selected.
Text callback scalars; positions and lengths are UTF-8 bytes, not JS indices.