This extension is for Windows and macOS.
A fully customizable, (and synchronous), alternative to GameMaker's default textbox input dialogs. Whether you want single-or-multi-line input, numbers-only or password entry, modal or sheet-modal (embedded dialogs!), setting the dialog size, or adding localization by changing button labels and other text, this extension pretty much has you covered. Everything you need for text entry.
Look for "icon.ico" included with the extension, (the one with the GameMaker logo), found in the extension's directory in your project folder, and replace it with your own icon of the same name and path as the original file to use your own desired icon on Windows. Mac will use whatever icon is used by the application bundle, which will be your game's custom icon on release builds.
The DLL's full source code included.
Very big thanks to Josh Ventura, for writing the widen() and shorten() scripts, enabling UTF-8 support on Windows.