Run the attached test and place the mouse anywhere except before the first character of the textbox.-Observe that the caret looks like a thick grey line.
Now place the mouse just before the first character of the textbox.-Observe that the caret now does not look like a thick grey line, but appears thinner or truncated.
This was seen on soma b28.
import javafx.scene.control.*;
import javafx.scene.*;
import javafx.stage.*;
var tb1 = TextBox {
    text: "ABC"
    columns: 12
    selectOnFocus: false
    editable: true
    translateX: 30
};
Stage {
    width: 300
    height: 200
    scene: Scene {
        content: tb1
    }
}