Fix DataGrid scrolling and coloring issues

[zoltanvi]

This PR improves the code quality and fixes some bugs:

• Could not scroll properly in Flow Launchers plugin page because the DataGrid swallowed the scroll event.
• The usage guide panel were incorrectly colored.
• The xaml code was inconsistently formatted

The grid grows dynamically with each new row.
The panel colors are tested in light and dark mode too.

Before:

After:

[Exarilo]

Hi,
Thanks again for your contribution !
I fully agree with the style changes that's better.
For the scrolling fix, in my case I have around a hundred rows, so being able to scroll is actually quite useful.
Maybe I can implement an alternative, like adding pagination or a scrollbar that only works with the mouse (no wheel), even if it’s a bit unusual.

[zoltanvi]

Hi, Thanks again for your contribution ! I fully agree with the style changes that's better. For the scrolling fix, in my case I have around a hundred rows, so being able to scroll is actually quite useful. Maybe I can implement an alternative, like adding pagination or a scrollbar that only works with the mouse (no wheel), even if it’s a bit unusual.

Hi,
Yeah, no worries 😄
Could you try out this branch to see if it works for you?
It's true that the scrolling is disabled on the DataGrid, but you can still see all items in it, and scroll the whole page, because the parent page handles the scroll.
If you insist on the old scrolling behavior, I can revert that part of the change, just let me know.

[Exarilo]

I tested the branch and everything works well on my side
It’s just that my DataGrid is huge, so I’m not sure what’s better between having a very large grid or a smaller one with a less convenient scrolling. 😅
I don’t know if others use my plugin the same way or if I’m the only one with so many rows.

[zoltanvi]

Yes, I can see that mine could be inconvenient as well.
I reverted those changes.

[Exarilo]

Thanks ! For now, I’ll integrate this, but I’ll also look into whether I can do something for the scrolling