How to set the default to Gaussian Blur

node_composite_blur.c

[...]

static void node_composit_init_blur(bNodeTree *UNUSED(ntree), bNode *node, bNodeTemplate *UNUSED(ntemp))
{
	node->storage = MEM_callocN(sizeof(NodeBlurData), "node blur data");
}

[...]

// Changes to:

static void node_composit_init_blur(bNodeTree *UNUSED(ntree), bNode *node, bNodeTemplate *UNUSED(ntemp))
{
	NodeBlurData* pNodeBlurData = MEM_callocN(sizeof(NodeBlurData), "node blur data");
	pNodeBlurData->filtertype = R_FILTER_GAUSS;
	node->storage = pNodeBlurData;
}