Avoid intellisense widgets being covered by the bottom panel

[r3inbowari]

Motivation

Avoid the problem that the Intellisense widget may be cover by the bottom(Output) panel partially.

Change description

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Reviewer checklist

• [ ] PR addresses a single concern.
• [ ] The PR has no duplicates (please search among the Pull Requests before creating one)
• [ ] PR title and description are properly filled.
• [ ] Docs have been added / updated (for bug fixes / features)

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[r3inbowari]

Agree :) Also fixed SplitPanel-handle showing above intellisense widget.

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[AlbyIanna]

This looks even better! I tested it and it works perfectly 😺 Thank you so much!