[Rendering] Sign updates flashing

[ghost]

Description of Issue

Updating a sign through the server(?) causes the entire sign to flicker instead of the thing that's selected.

Steps to Reproduce

Log into Hypixel, go to Skyblock, open the bankers menu, open the deposit/withdraw menu.

OptiFine Version

1.8.9 L5

Installation Method

Standalone & Forge.

Fabric/Forge Version

1.8.9 - 11.15.1.2318

F3 Debug Screenshot

Prior Testing

Doesn't happen in Vanilla, GIF provided.

[ghost]

update: noticed that this is a dupe of #3132, keeping open as mine provides visual representation

[ghost]

updating to mention that the bug may be caused by this method introduced in L5, not sure where the bug would lie in this, but it's the only thing that's changed in the TileEntitySignRenderer class besides L5 not replacing mc's lvt.
would be great if this could be fixed in L6 before that goes out of preview.

[ghost]

fully fixed this in my own mod Patcher (currently in beta as of writing this)

the fix was done as such:

add a public static field in GuiEditSign called whatever, i went with currentlyEditedSign
assign currentlyEditedSign in the GuiEditSign constructor to the teSign parameter
add currentlyEditedSign = null to GuiEditSign#onGuiClosed to ensure it cleans itself up
in TileEntitySignRenderer#isRenderText, on the line if (!Config.zoomMode && tileEntity.lineBeingEdited < 0) add && tileEntity != GuiEditSign.currentlyEditedSign

this issue is now fixed with those changes, perhaps get this into L6 along with #3474 as they're incredibly easy fixes and would essentially restore how i7 acted.

[DJtheRedstoner]

Please resolve this as well as #3616 and #1470 before 1.8.9 M5 pre2.

[sp614x]

Coming in M5_pre2.