In https://github.com/teelolws/EditModeExpanded/blob/main/Source/libs/EditModeExpanded-1.0/EditModeExpanded-1.0.lua#L734

When create EditModeExpandedSystemSettingsDialog, The default function UpdateSizeAndAnchors was overwrite, and it cause the dialog position in UIParent(400, 500), which might cover the frame we want to move, like this

I think we should add systemFrame:GetSettingsDialogAnchor():SetPoint(self, true) in it, or just use the original UpdateSizeAndAnchors function in EditModeSystemSettingsDialogMixin.
@teelolws

I found a much simpler solution, I'll just attach it to Blizzards dialog box like this:

Even works for the unusual situation where a default Edit Mode frame is selected, then a custom Edit Mode frame is selected - I do not de-select the default Edit Mode frame as that will taint the frame if I do:

I probably did that to stop something tainting. Most likely I traced UpdateSizeAndAnchors and found it was tainting the function if I use the original.

Edit mode is really sensitive, I have to be careful not to taint anything in EditModeSystemSettingsDialogMixin or the player starts getting errors when moving their target frames and such.

Instead of 400, 500 I should find the coordinates of the target frame, putting it to the left/right/top/bottom depending on which side of the screen the target frame is on. I'll need to find Blizzards code, see how they do it.

I probably did that to stop something tainting. Most likely I traced UpdateSizeAndAnchors and found it was tainting the function if I use the original.

Edit mode is really sensitive, I have to be careful not to taint anything in EditModeSystemSettingsDialogMixin or the player starts getting errors when moving their target frames and such.

Understand.
But maybe there is a better way to set it position rather than just use frame:SetPoint("TOPLEFT", UIParent, "BOTTOMLEFT", 400, 500)

Let me think about it. Thanks for your reply :)

Instead of 400, 500 I should find the coordinates of the target frame, putting it to the left/right/top/bottom depending on which side of the screen the target frame is on. I'll need to find Blizzards code, see how they do it.

I notice this addon and lib this afternoon, and want to use it in my own UI addon "Etern_UI".
Maybe I can help you to build EditModeExpanded together :)

I do not de-select the default Edit Mode frame as that will taint the frame if I do:

I just think about de-select the previous default Edit Mode frame when we select a custom frame use EditModeManagerFrame:ClearSelectedSystem() last night. I test many times and didn't found any taint issue.

How do you find the taint issue?

I might be able to just hide the Selection frame, without calling the full DeSelect functions. I'll try it out when I get some time.

Taint issue vs Taint. If I de-select it, it will taint the frame. This doesn't mean that it will cause problems, but I don't want to take the risk!

When I first wrote the addon, during 10.0.0, I was constantly getting "Addon Blocked Due to EditModeExpanded" errors so I coded it very carefully to not change any default Edit Mode code as much as possible.

Taint issue vs Taint. If I de-select it, it will taint the frame. This doesn't mean that it will cause problems, but I don't want to take the risk!

When I first wrote the addon, during 10.0.0, I was constantly getting "Addon Blocked Due to EditModeExpanded" errors so I coded it very carefully to not change any default Edit Mode code as much as possible.

Emmm, I understand, but I think pay too much attention on taint will limit our thinking.
Whatever, I will care more about taint later.

Sometimes yes, sometimes no. I don't truly understand why it does. Maybe if Blizzard code hooks the OnHide function?

I might be able to just hide the Selection frame, without calling the full DeSelect functions. I'll try it out when I get some time.

I will try it too. And I think I must review the taint page in fandom. :(

I was confused, will SetPoint/Show/Hide taint the frame and then taint the original path?

None that I know of. Just taint.log to see what tainted, or test global variables using https://wowpedia.fandom.com/wiki/API_issecurevariable

Sometimes yes, sometimes no. I don't truly understand why it does. Maybe if Blizzard code hooks the OnHide function?

Is there a way to check whether my action will taint frame/functions before a taint issue occurs.