SWindow with Custom FWindowStyle

Can’t seem to get my custom background brush, or any brush for that matter, to draw. It draws a flat grey background instead of the image. I’m assuming I’m doing something wrong in the code. This is in a standalone slate program.

Loading the background image in the custom style.

#define IMAGE_BRUSH( RelativePath, ... ) FSlateImageBrush( Style->RootToContentDir( RelativePath, TEXT(".png") ), __VA_ARGS__ )
#define BOX_BRUSH( RelativePath, ... ) FSlateBoxBrush( Style->RootToContentDir( RelativePath, TEXT(".png") ), __VA_ARGS__ )
#define BORDER_BRUSH( RelativePath, ... ) FSlateBorderBrush( Style->RootToContentDir( RelativePath, TEXT(".png") ), __VA_ARGS__ )
#define TTF_FONT( RelativePath, ... ) FSlateFontInfo( Style->RootToContentDir( RelativePath, TEXT(".ttf") ), __VA_ARGS__ )
#define OTF_FONT( RelativePath, ... ) FSlateFontInfo( Style->RootToContentDir( RelativePath, TEXT(".otf") ), __VA_ARGS__ )

TSharedRef< FSlateStyleSet > FMyStyle::Create()
{
	TSharedRef< FSlateStyleSet > Style = MakeShareable(new FSlateStyleSet(FMyStyle::GetStyleSetName()));
	Style->SetContentRoot(FPaths::GameContentDir() / TEXT("Slate"));

	Style->Set("MainWindow", FWindowStyle()
		.SetBackgroundBrush(IMAGE_BRUSH("MyImage", FVector2D(912, 582), FLinearColor::White, ESlateBrushTileType::NoTile))
		);

	return Style;
}

#undef IMAGE_BRUSH
#undef BOX_BRUSH
#undef BORDER_BRUSH
#undef OTF_FONT
#undef TTF_FONT

And usage of the custom style.

TSharedRef<SWindow> TestWindow = SNew(SWindow)
	.ClientSize(FVector2D(912, 582))
	.AutoCenter(EAutoCenter::PrimaryWorkArea)
	.Style(FMyStyle::Get(), "MainWindow");

FSlateApplication::Get().AddWindow(TestWindow);

For anyone else struggling with this you must absolutely define the following.

.SetOutlineBrush(BORDER_BRUSH("Common/Window/WindowOutline", FMargin(0.01f)))
.SetBorderBrush(BOX_BRUSH("Common/Window/WindowBorder", 0.01f))

Once I defined those my custom background appeared… with the default border but I’m going to assume if I specify that as well (and hopefully I can just specify an empty pixel) it will go away.