Enhance Global Drag-and-Drop feature for Upload component

[hujambo-dunia]

Addresses issue #16870
Changes include: larger drop zone, Toaster on file drop zone fail, and color highlighting

Updated wording

How to test the changes?

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• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[hujambo-dunia]

There is just one more change I need to make to ensure the drop-zone gets triggered on cases when the user first hovers over the center panel --hovering over the right or left panel immediately triggers the drop-zone but the center zone does not.

[hujambo-dunia]

There is just one more change I need to make to ensure the drop-zone gets triggered on cases when the user first hovers over the center panel --hovering over the right or left panel immediately triggers the drop-zone but the center zone does not.

Actually, I retract that last statement - it seems to be working about 95% of the time and I am unable to replicate it. Thought it might be a DOM Focus(); issue, but couldn't replicate it. Happens sporadically on Chrome for Mac OS. Provided the user who recommended it, accepts the change - I think we should move forward with the merge and just keep our eye open if the issue appears once it goes to the Production environment.

[ElectronicBlueberry]

I encountered something similar, when first developing this feature. It happens on the start page because of the iframe.
If you manage to move your mouse fast enough, so it appears directly within the iframe without traveling over any other components, the overlay will not show. I do not think this can be worked around.

[hujambo-dunia]

I encountered something similar, when first developing this feature. It happens on the start page because of the iframe. If you manage to move your mouse fast enough, so it appears directly within the iframe without traveling over any other components, the overlay will not show. I do not think this can be worked around.

@ElectronicBlueberry Thank you! I just got a good recommendation on how to test this potential IFrame issue so I can capture it for fixing. So will try that shortly and report back.