Resizable/toggleable panels and columns please? (!)

It's hard to complain about free software that works well and does what I need it to do without issue or ads or other BS... but this is really baffling to me. How hasn't this always been an option? And, with it not being an option, THIS is the solution? Can this PLEASE be addressed?

Resizable would be great. Toggleable would be alright if resizable wouldn't work for whatever reason. And, please, if neither of those, perhaps an explanation of why it can't be done? (whatever that reason is is fine, I mean for sake of understanding the technical issue behind it, not an 'explain yourself!'... just super sayin')

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