UIContentBlock: Add PrependSubBlock() to add a block in first position

sources/application/UI/Base/Layout/UIContentBlock.php

@@ -71,6 +71,19 @@ class UIContentBlock extends UIBlock implements iUIContentBlock
 		return $this;
 	}
 
+	/**
+	 * Add $oSubBlock as the first of the sub blocks, while preserving the array indexes
+	 *
+	 * @param \Combodo\iTop\Application\UI\Base\iUIBlock $oSubBlock
+	 *
+	 * @return $this
+	 */
+	public function PrependSubBlock(iUIBlock $oSubBlock)
+	{
+		$this->aSubBlocks = [$oSubBlock->GetId() => $oSubBlock] + $this->aSubBlocks;
+		return $this;
+	}
+
 	/**
 	 * @inheritDoc
 	 */