JavaFX remove padding/margin/border from Pane

Question

I can't seem to remove the left and right border of this GridPane. See picture below.

Left and Right border

My FXML file is

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<GridPane alignment="CENTER" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="800.0" style="-fx-box-border: transparent;" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8">
    <padding>
        <javafx.geometry.Insets  top="0" right="0" left="0" bottom="0"/>                 
    </padding>
    <columnConstraints>
        <ColumnConstraints percentWidth="33.0" />
        <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" percentWidth="33.0" prefWidth="100.0" />
        <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" percentWidth="33.0" prefWidth="100.0" />
    </columnConstraints>
    <rowConstraints>
        <RowConstraints minHeight="10.0" percentHeight="33.0" prefHeight="30.0" vgrow="SOMETIMES" />
        <RowConstraints minHeight="10.0" percentHeight="33.0" prefHeight="30.0" vgrow="SOMETIMES" />
        <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
    </rowConstraints>
    <children>
        <StackPane prefHeight="150.0" prefWidth="200.0" style="-fx-background-color: red;" />
        <StackPane prefHeight="150.0" prefWidth="200.0" style="-fx-background-color: red;" GridPane.columnIndex="2" GridPane.rowIndex="1" />
    </children>
</GridPane>

As you can see I already tried setting insets to 0, and making the border transparent but that doesn't work.

Answer 1

Your problem is simple - your columns have percentWidth set, but the total percent adds up to 99%, not 100%. Either change all of the percentages to 33.33..., or else change one of them to 34% while the other two remain 33%.

Answer 2

I know this long time over, but the better way would probably be to set percentWidth to 100 in each column.

The documentation states:

Note that if the sum of the widthPercent (or heightPercent) values total greater than 100, the values will be treated as weights. e.g. if 3 columns are each given a widthPercent of 50, then each will be allocated 1/3 of the gridpane's available width (50/(50+50+50)).

Setting to 100 will ensure in any number of columns that they will all have the same width.