First of all, love your mod, it's awesome <3.
I am playing with a lot of mods adding biters, unfortunately this increases the width of your GUI to screen width, hiding a lot of information behind the minimap.
I have changed your mod a little bit to make the GUI width a runtime-setting and added a scroll-bar to access everything: https://cdn.discordapp.com/attachments/236586880873791489/697550248393834589/unknown.png
Please get in touch with me so I can give you more information

Thanks for your love. These kind comments keep me motivated, letting me know these mods are worth my time. :-)

Yes, I am interested to add the horizontal scroll-bar. I do not use a lot of mods, so I am not aware of it.
I am relatively new to Factorio GUI programming, so if you can tell me what functions/properties I need to call, that would certainly be very helpful.

Some fine details:
1/ I wanted the scroll bar to exist only past a certain threshold. (Thus, the "softcore" players like me with only 4 types of spawners do not see the scroll bar at all.) So only the more "hardcore" players with many modded spawners would have to use the "width option". I am not sure how these could work together, before I really try implementing the code. Perhaps you will have a better idea.
2/ What are the mods you are using for such many types of spawners? (Where many of them seems the same to each other...)
3/ I have just an idea popped in my mind: adding a new option field for filtering on spawner name, which I have similarly done a lot in Schall Recipe Scaling allowing Lua pattern matching. So I can exclude spawner types generated by, for example, Creative Mod. (CM created a clone of every existing spawner, so making "redundant" entries like in your screenshot.) Not sure if it could be useful to your case.

Sorry for my late response, been a busy week
1/ The scroll bar actually already behaves like that , only if the content needs a scroll bar, that is, the content is too wide for the frame, a scroll bar appears
2/ I am using Armoured Biters, Swarmageddon and Rampant, I think it is just a problem with the sprites, because while there are a lot of biters they are quite different
3/ Filtering sounds like a great idea, would you like to create a github repo for your mod so we can work on it together?

The scroll bar is relatively easy to use, instead of adding the table to the frame directly I put it in a scroll pane inside the frame:
sp = frame.add {type = "scroll-pane", name = "scroll-pane_evo_frame", horizontal_scroll_policy = "always" }
sp.style["extra_left_padding_when_activated"] = 10
and then set the maximal framewidth to the setting or default of 1200:
local size_width = settings.get_player_settings(player)["endgameevolution-gui-size"].value
frame.style["maximal_width"] = size_width
sp.style["extra_right_padding_when_activated"] = 10

setting:
{
type = "int-setting",
name = "endgameevolution-gui-size",
order = "ee-g-4",
setting_type = "runtime-per-user",
minimum_value = 100,
maximum_value = 3000,
default_value = 1200
},

Thanks for the info.
These days I played with the GUI API a lot (including "scroll-pane") when making my private mod. I have found out how the scroll bar works with that.
I have learnt a lot about GUI style programming, so I think a big part of my current code can be improved and tidied up. The process is going to take some time. I guess I can finish the update this or next week. (Will also include the spawner filter as mentioned previously.)

I am not too interested in creating a Github repo yet, as I can still manage my mods well with constant updates. Having to maintain files on repo in sync takes additional time from me, yet do not offer too much benefits.
Maybe I will do this if I have less time and give up Factorio modding. But such a time has not come yet.
BTW, just realized I have released 42 mods now! (Not counting my private mods.) Putting them all to Github repo sounds like a job of madness...

Versions 0.17.11 / 0.18.3 both allow setting frame width and height, are just released.
I did with my own code, but should achieve the same purpose.

The spawner name filter is also implemented, try it out and tell me if it works well for you.

Anyone else have crash when clicking evolution icon?
Using factorio 18.19 or 18.21 both crashes for endgame 18.3

Can you provide the error message, or screenshot of it?