Allow horizontal scroll with Shift key

[feinstein]

When I open the Devtools in Firefox I can only scroll vertically with my mouse. It would help a lot if the Shift key were made as a modifier to scroll horizontally the widget tree.

[Piinks]

Related to flutter/flutter#75180
This should currently be possible on mac platforms, but it has yet to be implemented in the engine for other platforms. There was some discussion in the linked issue of checking the keyboard state when handling a pointer scroll and adjusting accordingly, so that may be a beneficial workaround as there are a lot of customized scrolling widgets here that have been forked from the framework. :)

[feinstein]

Interesting, thanks @Piinks!

[Piinks]

Sure thing! I also just remembered, the mouse type matters. For example, an Apple magic mouse is like a trackpad rather than a typical mouse with a physical scroll wheel.

[feinstein]

And this same view on Android Studio allows me to drag and move it around.

[kenzieschmoll]

We are still seeing this on linux from a g3 customer. We should investigate.

[Piinks]

This may help: flutter/flutter#115610 :)

[JerContact]

@Piinks is this in latest flutter or when can we expect this to be in the master branch?

[BrunoRoemers]

Horizontal scroll with shift key does not work most of the time in the Widget Tree of the Widget Inspector.

It is unfortunate because it's a standard UI convention that has become part of my muscle-memory, and it slows down debugging.

When does it work?

• The VSCode window has focus, the mouse pointer hovers over the bottom scroll bar, I hold shift and turn the scroll wheel. => It scrolls horizontally as expected.
• The VSCode window does NOT have focus, the mouse pointer hovers anywhere in the Widget Tree, I hold shift, and I turn the scroll wheel. => It scrolls horizontally as expected.

When does it NOT work?

• The main use case: The VSCode window has focus, the mouse pointer hovers anywhere in the Widget Tree, I hold shift, and I turn the scroll wheel. => It scrolls vertically instead of horizontally.

Mac Sonoma 14.4.1 + VSCode 1.89.1

[kenzieschmoll]

CC @elliette for Inspector scrolling.