unable to add widgets to object inspector in qt creator/designer

[abiabi]

iam unable to add objects to object inspector tab in qt creator while editing ui files.the only way to add is by the canvas.(the center drag and drop area).
here is screen recording https://streamable.com/9bn1yk?src=player-page-share!

the problem is sometimes some objects in drag and drop area willbe visually small or sometimes we cannot visually identify things from that drag and drop area.
so if we want to add objects to gui accurately or fast way then object inspector is better way .

why it is not possible in qt creator/designer
is it actually a bug or am i wrong because of little experience.