Misalignment of Double-Width Characters with Dialog Utility's --column-separator Option

[sunnycemetery]

Here is a simple test:

> dialog --column-separator '|' --radiolist 'DOUBLE-WIDTH ALIGNMENT TEST' 0 0 0 g 
> 'Great|Grits' 0 j 'Jolly|Juice' 0 m 'マーベラスな|味噌汁' 0

Here is the output:

> ┌─────────────────────────────────────────┐
> │ DOUBLE-WIDTH ALIGNMENT TEST             │
> │ ┌─────────────────────────────────────┐ │
> │ │ ( ) g  Great              Grits     │ │
> │ │ ( ) j  Jolly              Juice     │ │
> │ │ ( ) m  マーベラスな 味噌汁          │ │
> │ └─────────────────────────────────────┘ │
> │                                         │
> │                                         │
> ├─────────────────────────────────────────┤
> │         < 了解 >     < 取消 >           │
> └─────────────────────────────────────────┘

And here is the expected output:

> ┌─────────────────────────────────────────┐
> │ DOUBLE-WIDTH ALIGNMENT TEST             │
> │ ┌─────────────────────────────────────┐ │
> │ │ ( ) g  Great              Grits     │ │
> │ │ ( ) j  Jolly              Juice     │ │
> │ │ ( ) m  マーベラスな       味噌汁    │ │
> │ └─────────────────────────────────────┘ │
> │                                         │
> │                                         │
> ├─────────────────────────────────────────┤
> │         < 了解 >     < 取消 >           │
> └─────────────────────────────────────────┘

(Hopefully your MUA uses a monospaced font.)

I am using dialog 1.3-20181107.  Interestingly, alignment of the tag/item 
columns *does* seem to account for double-width characters:

> dialog --radiolist 'DOUBLE-WIDTH ALIGNMENT TEST' 0 0 0 g 'Great Grits' 0 j 
> 'Jolly Juice' 0 マ 'マーベラスな味噌汁' 0

Output:

> ┌────────────────────────────────┐
> │ DOUBLE-WIDTH ALIGNMENT TEST    │
> │ ┌────────────────────────────┐ │
> │ │ ( ) g   Great Grits        │ │
> │ │ ( ) j   Jolly Juice        │ │
> │ │ ( ) マ  マーベラスな味噌汁 │ │
> │ └────────────────────────────┘ │
> │                                │
> │                                │
> ├────────────────────────────────┤
> │     < 了解 >   < 取消 >        │
> └────────────────────────────────┘

Proper alignment of double-width characters is also demonstrated in the 
following snazzy screenshot:

https://invisible-island.net/dialog/dialog.html#screenshot

So is this a bug?  Thank you for reading.