XdevCollapsiblePane: property background color for the contentpane
Description
Initial behaviour:
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I create a XdevWindow with a XdevCollapsiblePane.
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Real behaviour:
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At the moment I can not change the background color of the "contentpane". The default background color is white.
The property "Color" from the XdevCollapsiblePane only change the title color.
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Expected behaviour:
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I can change the background color via property from the contentpane.
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Environment
None
