How can I install Tcl/Tk 8.7 alpha version. I use only the official repository but turned on the others to see if it is available but could not locate it. If it is not in a repository is there a safe way to install it? Thank you.
Given that it’s only an alpha release, most distributions will shy away from adding it to their repos. However, if you’re brave enough, then you can download the source code and build it yourself on your local machine.
You could copy the official Arch Linux PKGBUILD
https://github.com/archlinux/svntogit-packages/tree/packages/tcl/trunk
Then modify - pointing to the alpha source and build it.
You should be able to personally troubleshoot your system when any weird issues arise - including seemingly unrelated to your custom build.