Possible to have two sections collapse with one action?

I think this is not directly supported as the property whether the section is collapsed or not is not exposed. The only way I can think of is to create your own collapse/expand controls and switch between an empty section (showing expand link) and an expanded section.

This is exactly what I made, using a button but, it would be nice to have the information about if the section is collapsed saved so we can use it to collapse or not another section. The collapse item is better in term of user experience than a button for that.

Hi Mokhtar, personally I wouldn't use buttons for this as it provides inconsistency to look and feel of Appian solutions. Consider using putting your section title in a richTextDisplayField() with one of the header styles and combine it with a dynamicLink to hide and show the section.

This can be achieved with 17.2 version in which we have the concept of columns and column layout.
You can have once section and then inside contents you can have two columnsLayout inside that and then replace other sections with columnLayout.

a!sectionLayout(
label: "Test0",
isCollapsible: true(),
contents: {
a!columnsLayout(
columns: {
a!columnLayout(
a!textField(
label: "Test"
)
)
}
),
a!columnsLayout(
columns:{
a!columnLayout(
a!textField(
label: "Test1"
)
),
a!columnLayout(
a!columnLayout(
a!textField(
label: "Test2"
)
)
)
}
)
}
)