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active-tab-width

The plugin gives a way to automatically resize the currently selected (focused) tab to X% of the screen
nudelx
115

tree-view-full-width

While crawling through directories, this package will give tree view the ability to keep the tree view extended fully. It also disables the extender, so if that doesn't bother you, you're in luck!
gillerg8
130

full-width-tabs

full width of the tabs for better visualization
luisDanielRoviraContreras
161

atom-auto-resize

Keep Atom window minimal by resizing it automatically when panes/docks are opened or closed.
keskiju
55