fix: Fixup preview rendering and logic of preview key binding being shown in shortcut list

[cartercanedy]

Fixup rendering of floating text and logc of preview key binding being shown in shortcut list

Type of Change

• New feature
• Bug fix
• Documentation Update
• Refactoring
• Hotfix
• Security patch
• UI/UX improvement

Description

Any floating content that gets rendered has the possibility of rendering any text from the underlying widget. Prior to drawing the float content, the area that the float content is rendered to should be cleared prior to drawing the float content.

Impact

Having extraneous text present within the preview area might confuse users if the text that is presented from the underlying widget looks like valid bash. This removes the possibility for confusion.

Also, the key binding for showing the preview isn't rendered if the list widget is at the top-level dir of a category, but is properly shown in subdirs. The previewing capability is pretty nifty and should be properly displayed as a key binding when valid.

Issue related to PR

• Resolves preview shortcut isn't shown if the selection is in the top-level dir of a command category #385
• Resolves text from widgets underneath aren't properly cleared before rendering the float content #386

Checklist

• My code adheres to the coding and style guidelines of the project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no errors/warnings/merge conflicts.

[nnyyxxxx]

Thanks

[jeevithakannan2]

Please remove these lines from the code

https://github.com/ChrisTitusTech/linutil/blob/main/tui%2Fsrc%2Ffloating_text.rs#L105-L108

Your implementation is better and these lines are not necessary if this is merged

[jeevithakannan2]

@ChrisTitusTech please implement the above requested changes before merging