Yad - Yad (yet another dialog) is a fork of Zenity with many improvements, such as custom buttons...
HTML-Notepad - HTML WYSIWYG editor for structured documents
Glade - Glade is a RAD tool to enable quick & easy development of user interfaces for the GTK+ toolkit...
Notepadqq - Notepadqq is a linux clone (identical application) of Notepad++
wxFormBuilder - wxWidgets is an excellent framework that enables the creation of multi-platform applications with...
iNotepad - Write and organize all your texts and notes on Mac.