Merge pull request #438 from iriusrisk/feature/BLAZ-1642

[feature/BLAZ-1642] to dev

Author: smaneroiriusrisk

slp_drawio/resources/schemas/drawio_schema.xsd

@@ -66,6 +66,7 @@
         <xs:attribute type="xs:string" name="pageHeight"/>
         <xs:attribute type="xs:string" name="math"/>
         <xs:attribute type="xs:string" name="shadow"/>
+        <xs:attribute type="xs:string" name="background"/>
     </xs:complexType>
     <xs:complexType name="diagramType" mixed="true">
         <xs:sequence minOccurs="0" maxOccurs="unbounded">