gmail-scc is a free Chrome add-on developed by 毒眼鏡 that allows users to change the size of the sidebar column in Gmail. With this add-on, users can easily adjust the width of the sidebar from the default 176px to a wider 255px.

The add-on comes with version history information, with the latest update being version 0.4. This update includes a change in the Japanese description. The previous version, 0.3, introduced multilingualization, making it accessible to users who prefer languages other than English. Version 0.2 brought a wide column change to the compose button, enhancing the user experience. The initial release of the add-on was version 0.1.

In terms of future updates, gmail-scc aims to provide users with the freedom to set the sidebar column width to any desired value up to 255px. Additionally, the add-on plans to incorporate a drag-and-drop feature, allowing users to easily resize the sidebar column according to their preferences.

However, it's important to note that this add-on does not currently support certain behaviors when the labs feature is enabled.

Overall, gmail-scc is a handy Chrome add-on for Gmail users who wish to customize the sidebar column size and improve their email management experience.