messagebox

Opens a Windows message-box popup and returns the code of the button the user clicked.

messagebox(text: string, caption: string, flags: number): number

text is the popup body, caption is the title bar, and flags is a number that packs three things at once: the button set in the low 4 bits, an icon, and which button starts selected. The value passes straight to Win32’s MessageBoxA, so the codes below come from Microsoft’s docs.

Most commonly used to ask the user to confirm before a script does something they can’t undo.

Calling messagebox freezes the entire Roblox client until the user dismisses the popup. Visuals don’t redraw, input doesn’t register, and no Luau coroutine runs while it’s open.

Common button styles (low 4 bits, mutually exclusive):

• 0 - MB_OK: just OK
• 1 - MB_OKCANCEL: OK and Cancel
• 3 - MB_YESNOCANCEL: Yes, No, and Cancel
• 4 - MB_YESNO: Yes and No

Icon bits (added to the button style for a coloured icon next to the text):

• 0x10 - red error
• 0x20 - question mark (deprecated by Microsoft but still works)
• 0x30 - yellow warning triangle
• 0x40 - blue info (i)

flags = 4 + 0x30 opens a Yes/No popup with the warning icon. Default-button selectors (0x100, 0x200, 0x300) and rarer button sets (Abort/Retry/Ignore, Cancel/TryAgain/Continue) live in the Microsoft docs.
Learn more here.

Parameters

Parameter	Type	Description
text	string	Body text shown inside the popup.
caption	string	Title bar text.
flags	number	Bitfield - button style, optional icon, optional default-button.

Returns

number - the Win32 ID constant for the button the user clicked:

Value	Constant	Triggered by
1	IDOK	OK
2	IDCANCEL	Cancel
6	IDYES	Yes
7	IDNO	No

Example

Example 1

<<<<<<< HEAD
local choice = messagebox("Click OK to continue", "Alert", 0)
=======
-- messagebox(text: string, caption: string, flags: number): number
>>>>>>> 50e30f53759b0538759af25c9b271514aa2c9290

Calling messagebox freezes the entire Roblox client until the user dismisses the popup. Visuals don’t redraw, input doesn’t register, and no Luau coroutine runs while it’s open.