Hi, I think the issue is you're passing a Gamemaker constant to setCursorColor instead of a Scribble color tag, which in turn is printing the color number as part of the blinking cursor text, possibly hiding the text.
I assume you're using 2025.11 and latest Gamemaker, but let me know.
For reference this is the corrected code, which only changes setCursorColor, I added a modal panel and a grid like you said, and the textbox to a grid cell:
var _panel = new UIPanel("Panel", 0, 0, 500, 400, grey_panel, UI_RELATIVE_TO.MIDDLE_CENTER); _panel.setModal(true);
var _grid = new UIGrid("Grid", 3, 3); _panel.add(_grid);
var _seedInput = new UITextBox("seedInput", 0, 16, 148, 24, blue_button00, 8); with (_seedInput) {
setAllowDigits(true);
setAdjustHeight(false);
setMultiline(false);
setPlaceholderText("0");
setCursorChar("_");
setCursorColor("[c_white]");
setReadOnly(false);
setTextAnchor(UI_RELATIVE_TO.MIDDLE_CENTER);
setInheritWidth(true);
setCallback(UI_EVENT.VALUE_CHANGED, function() {
show_debug_message(ui_get("seedInput").getText());
});
}
_grid.addToCell(_seedInput, 1, 1);This is the result:

Let me know if you have more problems.