Results background color inconsistent while searching duplicates and similar images

[juozaspo]

While searching for duplicates & similar images the background of search results is inconsistent. In checkbox column where is no checkbox there is white background everywhere else is like in dark theme and remaining background remains white. Screenshot:

Czkawka version: 3.1.0 (da76f75), compiled from source.
OS: Ubuntu Linux 20.04 LTS
Desktop environment: Xfce 4 with Greybird light theme
Rust compiler verion: 1.54.0 (a178d0322 2021-07-26)
Cargo version: 1.54.0 (5ae8d74b3 2021-06-22)
Development libs packages:

• libasound2-dev: 1.2.2-2.1ubuntu2.4
• libgtk-3-dev: 3.24.20-0ubuntu1

[qarmin]

White theme is not fully supported because I don't know exactly how to add different color to header rows in list store.
I don't want to use tree store since it is less performant.

[siodor]

@qarmin
How about using the white space for a checkbox which (un)selects the whole group of files?

[qarmin]

In #450 I filled this empty space, but for now new button don't do anthing