Fix empty space at bottom of Functions widget

[manideepikapasarthi]

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Detailed description

This pull request fixes the extra empty space visible at the bottom of the Functions widget.

The issue was caused by the tree view not expanding properly within the dock widget.
This change updates the size policy of the tree view to allow it to expand correctly and enables the vertical scrollbar only when needed.

No functional behavior is changed; this is a UI/layout improvement only.

Test plan (required)

1. Open Cutter.
2. Load any binary with multiple detected functions.
3. Open the Functions widget.
4. Resize the window and dock area.

Result:

• The Functions widget no longer shows unnecessary empty space at the bottom.
• The tree view expands correctly.
• Vertical scrollbar appears only when required.

Closing issues

closes #2789

[wargio]

please provide screenshot before and after.

[manideepikapasarthi]

Hi! Here is a screenshot showing the bug on the unpatched v2.4.1 release — the Functions widget shows a large empty space below the last function entry when the panel is resized vertically.

My fix adds setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding) to the tree view, which tells Qt to fill all available vertical space with the list instead of leaving unused blank space. I also cleaned up a redundant line in my latest commit to keep the change minimal.

[Rot127]

Please provide us with a "after" screenshot with the fix applied.

[PremadeS]

I'm pretty sure the empty space is caused by the status bar not showing any text initially. Try searching for something in the quick filter box. Setting the sizePolicy to Expanding isn't going to do much in this case

See #1923

[wargio]

then maybe we should show something like the initial total amount

[PremadeS]

then maybe we should show something like the initial total amount

For now, sure

But as a long term fix, putting the count indicator alongside the quick filter instead of being below is better. Also allowing the user to fully hide the count indicator through settings seems reasonable IMO
It's also mentioned in the issue I linked above (#1923)