Can't center inside of a grid both vertically and horizontally.

I'm totally not sure whether that's a bug, or anything, but I've read through the docs couple of times, and for example this code that seems to overdo it but convey what I want:
```
ui.with_layout(Layout::left_to_right(Align::Center).with_main_align(Align::Center).with_cross_align(Align::Center), |ui| {
ui.label(format!("{:?}", v));
});
```
Results in vertical alignment to center, and main alignment to left.

The only code I've found through trial and error that is capable of centering it horizontally is this:
```
ui.with_layout(Layout::top_down(Align::Center).with_cross_align(Align::Center), |ui| {
ui.label(format!("{:?}", v));
});
```
But of course, then it's vertically aligned on the very ceiling of the cell.

The crux of the problem is that this
```
ui.with_layout(Layout::left_to_right(Align::Center).with_main_align(Align::Center), |ui| {
ui.label(format!("{:?}", v));
});
```
centers vertically, not horizontally, inside Grid. (which seems to be default centering inside Grid along vertical axis)