Positioning of Components
Size types

Component dimensions, width and height, can be of the following types:

  • Content-based - AUTO

  • Fixed (pixels) - 10px

  • Relative (percent) - 100%

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Content-dependent size

The component will take enough space to fit its content.


  • For Label, the size is defined by text length.

  • For containers, the size is defined by the sum of all component sizes inside a container.

<label width=AUTO/>

Components with content-dependent size will adjust their dimensions during screen layout initialization or when the content size is changed.

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Fixed size

Fixed size implies that the component dimensions will not change at runtime.

<vbox width=320px height=240px/>
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Relative size

Relative size indicates the percentage of available space that will be occupied by the component.

<label width=100%/>

Components with relative size will react to changes in the amount of the available space and adjust their actual size on the screen.

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Container specifics

By default, containers without the expand attribute provide equal space for all nested components. Exceptions: flowBox and htmlBox.

For example:

    <button caption="Button"/>
    <button caption="Button"/>
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Components and containers width and height are content-dependent by default. Some containers have different default dimensions:

Container Width Height










The root layout element is a vertical container (VBox), which has 100% width and height. The height can be AUTO in dialog mode.

Tabs within a TabSheet are VBox containers.

GroupBox component contains a VBox or an HBox, depending on the orientation property value.

Example of a container with content-based size:

        <button caption="Button"/>
        <button caption="Button"/>
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Example of a container with relative size:

<layout spacing="true">
    <groupBox caption="GroupBox"
    <button caption="Button"/>
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Here, layout, as well as vbox or hbox, provides equal space to all nested components, and groupBox has 100% height. In addition to that, groupBox has 100% width by default and takes all the available space.

Component specifics

It is recommended to set the absolute or relative height for Table and Tree. Otherwise, a table/tree can take unlimited size, if there are too many rows or nodes.

ScrollBox must have fixed or relative (but not AUTO) width and height. Components inside ScrollBox, positioned in the scrolling direction, may not have relative dimensions.

The following examples show the correct use of horizontal and vertical ScrollBox containers. If scrolling is required in both directions, both height and width must be set for the components (AUTO or absolute).

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The expand option

The container’s expand attribute allows specifying the component that will be given maximum available space.

The component specified in expand will have 100% size in the direction of the component expansion (vertically - for VBox, horizontally - for HBox). When container size is changed, the component will change its size accordingly.

<vbox expand="bigBox">
    <vbox id="bigBox"/>
    <label value="Label"/>
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expand works relatively to component expansion, for example:

<layout spacing="true"
    <groupBox id="groupBox"
    <button caption="Button"/>
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In the following example, the auxiliary Label element (spacer) is used. Due to applied expand, it takes all the space left in the container.

<layout expand="spacer">
    <textField caption="Number"/>
    <dateField caption="Date"/>
    <label id="spacer"/>
    <hbox spacing="true">
        <button caption="OK"/>
        <button caption="Cancel"/>
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