(This bugpost is being reworked, many graphics, also of newer GUIs, are missing, as well as texts, due to character limitation; "perfect GUI" pack will be eventually provided)

Generally, it may be good (if it doesn't already exist) to have a GUI library, after "the perfect GUIs" have been created, so future GUIs should be automatically in those "perfect GUI" boundaries, and things such as e.g. headlines/texts would be also correctly positioned.

It would be great if all GUIs could be fixed relatively close time-wise, so resource pack makers don't have to rework their GUIs that often, or that their fix would be done over the course of a longer snapshot period/before a full release.

Some GUI textures are repurposed, e.g. Dispenser with Dropper, or all chest-like types with each other share a GUI texture.
This is a problem for resource pack makers, as they can't give each GUI an individual look.
See bugpost: MC-173383

Mix of old and new text and graphics, until bugpost has been fully updated:

There's no single MC GUI which is consistent towards every other GUI, in all GUIs are various issues; some fixes would be few or minor, some GUIs have several issues at the same time. In this bugpost I demonstrate inconsistencies as well as possible fixes.
As this bugpost exceeds the allowed 20,000 characters, I'll reduce it to my personal favourite fixes, hopefully most consistent GUI fix solutions, for overall GUI harmonizing and maximum "OCD".

Quick issue breakdown: There are offsets of the "Inventory" headline as well as the main headlines (e.g. "Chest"). Some GUIs are of same total height, but the "Inventory" headline area is 1 pixel too short (12 vs. 13 pixel) or the "Main" headline area with the GUI's name/title is 1 pixel too tall (14 vs. 13 pixel); there are offsets of either one or both of the titles/headlines or even of the location of the "(tile) entity content area". And then there are other issues on some GUIs which are not related to the "inventory" or "main" headline area like for example the usage of not common (on MC GUIs) used distances, and sometimes all of the described problems mixed up together (it will become clearer if you have a look at the graphics).

There is no single "correct" GUI as for the location of the "main" as well as "Inventory" headline,
so I created one, on the basis of the Dropper GUI:
_Correct-GUI-base.png

It seems there are 5 different GUI problem groups with 7 different recurring "problem zones";
Red means there's an inconsistency or problem, Green means this "problem zone" is correct.

(1)

• GUI total height: 1px too tall (generic_54.png; faulty texture is shared amongst most chest-like GUIs which seems to lead to offsets)
• Location "Main Headline Text" (e.g.: "Chest"): 1px too high
• Total "Main Headline Area Height": 1px too tall (14 vs 13 px)
• "(Tile) Entity Content Area Location": OK
• Location "Inventory" text: OK (3px space above and below it)
• Total "Inventory Headline Area Height": OK (13 px)**

Affects:

• • SingleChest; issue visualization:
    _(1)_chest.png
    Offset-Issue-Demonstration-Video:
     chest_gui-offset-comparison.mp4
• • DoubleChest
    

• • Minecart with Chest
  • Ender Chest

(2)

• GUI total height: OK
• Location "Main Headline Text" (e.g.: "Shulker Box"): OK
• Total "Main Headline Area Height": 1px too tall (14 vs 13 px)
• "(Tile) Entity Content Area Location": 1px too low
• Location "Inventory" text: OK
• Total "Inventory Headline Area Height": 1 pixel too short (12 vs 13 px)
• TLDR: Shulker Box inventory needs to be moved up 1 pixel to fix this GUI

Affects:

• • Shulker Box; issue visualization:
    _(2)_shulkerbox.png

    	<<< fixed shulker box png incl. markers and English text to see where Vanilla GUI deviates

(3)

• GUI total height: OK
• Location "Main Headline Text" (e.g.: "Mule"): OK
• Total "Main Headline Area Height": 1px too tall (14 vs 13 px)
• "(Tile) Entity Content Area Location": 1px too low
• Location "Inventory" text: 1px too high
• Total "Inventory Headline Area Height": 1px too short (12 vs 13 px)

Affects:

• • Horse
  • Donkey
  • Mule; issue visualization:
    _(3)_mule.png
  • Llama

(4)

• GUI total height: OK
• Location "Main Headline Text" ("Enchant"): 1px too high
• Total "Main Headline Area Height": 1px too tall (14 vs 13 px)
• "(Tile) Entity Content Area Location": 1px too low
• Total Tile Entity Area Height: 5px too tall (at least probably; will try to find a working solution)
• Total "Inventory Headline Area Height": Due to the enchantment slots area being 5px too tall, cuts 2px into it.
  Can be maybe ignored, as long as the word "Inventory" in all available languages would not be much longer than the English word.

Affects:

• • Enchantment Table; issue visualization:
    _(4)_enchanttable.png

(5)

• GUI total height: OK
• Location "Main Headline Text" ("Crafting"): Offset or generally not following consistency with the other GUIs
• Total "Main Headline Area Height": OK
• "(Tile) Entity Content Area Location": OK
• Location "Inventory" text: 1 pixel too high
• Total "Inventory Headline Area Height": not used or rather intersected with an offset "Enchantment Cost" text when item is placed into Anvil.

Affects:

• • Crafting Table - The main headline "Crafting" is either offset by 1 pixel too far to the left or should be matching up left where also "Inventory starts" or should be centered. Both, being located at the left like "Inventory" as well as being centered is common with MC Vanilla GUIs, so it makes no sense to not do either of both for the Crafting Table. "Inventory" text is located 1 pixel too high. Issue visualization:
    _(5)_craftingtable.png

Fixes

• • V1 - Moving 1px to the right (like "Crafting" is lined up in the Player Survival Inventory) :
    CraftingTable_Fix1-Comparison.png
  • V2 - Moving "Crafting" to where "Inventory starts, to the left:
    CraftingTable_Fix2-Comparison.png
  • V3 - Centering "Crafting" over the Crafting Grid:
    CraftingTable_Fix3-Comparison.png
  • V4 - Centering "Crafting" over the complete GUI:
    CraftingTable_Fix4-Comparison.png
    For consistency reasons, V3 or V4 would be probably the best solution, but of course the final decision is up to Mojang.
  • Original GUI and all 4 Fix proposals in one comparison-picture:
    CraftingTable_Orig-AndAllFixes-Comparison.png

• • Player Survival Inventory - Differing from the Crafting Table, "Crafting" is lined up nicely with the upper left crafting grid slot.
    However, for consistency, it would probably look best to also have it centered.

• • Furthermore for more consistency, "Crafting" should move up 1px to not only line up with the upper edge of the player armour and display area (everything 4px apart from the GUI edges, as it should consistently be), but also to have consistency in the distance of a headline towards the next GUI content, which is 3px; all correctly located headlines, be it the "main" GUI headline or the "Inventory" headline got a 3 pixel space below and above them, so by moving "Crafting" in the Player Survival GUI 1px up, we'd have also that consistency in the distance to the crafting grid (= 3px), so, overall a more harmonized and consistent GUI.

• • The distance from the crafting result slot to the right GUI edge is another major inconsistency issue:
    Unlike other (similar) GUIs, the slot is only 2px apart from the right edge, whereas it should be 4px.
    Note: 4px is a common distance to GUI edges, also here in this case, e.g. the player inventory is also always 4px apart from the left, right and bottom edge, and in this GUI also the Armour Slots + Player Display are 4px apart from the top and left edge; lastly, the shield slot is also 4px apart from the player inventory, so it makes no sense to have the crafting area only 2px apart from the right edge, as it's possible to move it 2px to the left, so it'd be as a result also nicely 4px apart from the right edge. Issue visualization:
    _(5)_playersurvival.png

Fixes

• • V1 - Moving the "Crafting" text 1px up and centering it over the player crafting grid
  • V2 - Like V1 and moving the whole crafting area 2px to the left, so the crafting result slot would be now consistent 4px apart from the right GUI edge (and 1px, not 3, from where the shield slot begins)
    PlayerSurvival_Orig-AndAllFixes-Comparison.png
    PlayerSurvival_Fix-Comparison.png
    PlayerSurvival_Fix-Comparison_closeup.png

Other Issues in other GUIs

• GUI total height: OK
• Location "Main Headline Text" ("Repair & Name"): OK
• Total "Main Headline Area Height": OK / here not of importance
• "(Tile) Entity Content Area Location": OK
• Location "Inventory" text: Currently not present
• Total "Inventory Headline Area Height": not used/intersected with offset "Enchantment Cost" text when item placed into Anvil
• "Deviation to other common MC GUI distances": The original GUI uses 10/12/14/18px distances, not only the common 3/4/13px; e.g. the Hammer graphics is 14px apart from the left edge, not 13px, and only 12px from the Rename Slot, not 13px.

Affects:

• • Anvil
    Issue visualization:
    Anvil_Issue.png

Fix

• • V2 - The most consistent change would be to use the common MC GUI distances of 3/4/13px, which would be good for overall GUI consistency:
    
    V2 would be the most consistent change, as it follows the usual "3/4/13px-rule" as for distances in the MC GUIs.*
    Furthermore, by adding "Inventory" headline, it's advisable to move "Enchantment Cost" to the top, as there would be overlap with higher XP levels cost, as well as potentially in languages other than English.**

---- - GUI total height: OK

• Location "Main Headline Text" (e.g.: "Brewing Stand"): OK or uncertain (should be centered horizontally)
• Total "Main Headline Area Height": Ok
• "(Tile) Entity Content Area Location": 1px too low
• Location "Inventory" text: 1px offset horizontally and vertically
• Total "Inventory Headline Area Height": Ok
• "Deviation to other common MC GUI distances": No comparison, special GUI
• Special remarks: Hard to word in short; for this GUI to be symmetrical, the graphics part to the right of the distillery graphic part needs to be moved 1px to the right, distillery graphic needs to be retouched a little (1px longer); more graphic fixes: uppermost bubble must move 1px down. arrow needs to move 1px up

Affects:

• • Brewing Stand
    Issue visualization + Fix:
    

• "Deviation of common MC GUI distances"
  Issue-Demo-Video:

 brewingstand_comparison.mp4

I might still not have the total picture of the GUI issue yet, will update this bugpost accordingly when I'm through with all individual GUIs.

---

Note: 13 pixel are a common distance from a graphics on a GUI to the edges of the GUI; 13 pixel is e.g. the distance in the GUI between the player inventory and the GUI above, the area where the headline "Inventory" is displayed, as well as between the "(Tile) Entity Inventory/Content Area" and the top of the GUI. Visualized in the individual GUI graphics with blue (or a blue square).
4 pixel also are a common distance within the GUIs, visualized on the individual GUI graphics by the colour pink (or a pink square).
3 pixel is the correctly middle-centered distance of the main and Inventory headline up- and downwards, visualized on the graphics by the colour purple (or a purple square).
2 pixel are visualized in lime green (or a lime green square).
1 pixel is visualized in aqua (or an aqua square).

---

• Anvil - "Inventory" text 1px too high. "Enchantment cost" text seems out of place.
  Deviation of common MC GUI distances: The original GUI uses 10, 14, 18px distances, not the common 4px/13px.
  Fix V2 is consistent with common MC GUI distances and would be the most consistent GUI.
  Issue-Graphics: Anvil_Issue.png
  Fixes-Graphics: [^Anvil_Fix1-Comparison.png] Anvil_Fix2-Comparison.png [^Anvil_Fix3-Comparison.png]
  Anvil_Orig-AndAllFixes-Comparison.png

• Brewing Stand - (Issue text+visualization graphics still in the making) See MC-114363 - I explained in the comments more of the offset problems in that GUI than described in the bugpost. Reworked, albeit not 100% "OCD-proof" brewing stand Default GUI also attached here, as well as a short video comparing the original and reworked GUI. "Inventory" text 1px too high.
  Issue-Demo-Video: brewingstand_comparison.mp4

• Crafting Table The distance of the crafting result slot to right edge is offset by 2px, compared to the distance on the left; solution: add 1px each at left and right of the arrow. Furthermore, main headline ("Crafting") is offset by 1px to the left, but for consistency reasons it'd be probably best to have "Crafting" centered above the crafting grid, like also e.g. for Dropper, Dispenser, Furnace etc., as well as moving "Crafting" up by 1px, so it'd be 3px apart from the crafting grid (which would be consistent with any other correctly positioned headline) and 4px apart from the GUI top edge, which would be consistent to the default/consistent 4px distance on/towards Vanilla GUI edges.
  Issue-Graphics: _(5)_craftingtable.png
  Fixes-Graphics: CraftingTable_Fix1-Comparison.png CraftingTable_Fix2-Comparison.png CraftingTable_Fix3-Comparison.png
  CraftingTable_Fix4-Comparison.png CraftingTable_Orig-AndAllFixes-Comparison.png

• Dispenser - "Inventory" text 1px too high

• Dropper - "Inventory" text 1px too high

• DoubleChest - Same as "SingleChest" (described there)

• Enchantment Table -
  Issue-Graphics: _(4)_enchanttable.png

• Ender Chest - Same as "SingleChest" (described there)

• Furnace - "Inventory" text 1px too high

• Hopper - "Inventory" text 1px too high

• Horse, Mule, Donkey, Llama - "Entity Content Area" located 1px too low, causing "Inventory Headline area" to be 1 pixel too short; caused by 1 pixel too tall "main headline area"; "Inventory" text 1px too high.
  Issue-Graphics: _(3)_mule.png

• Minecart with Chest - Same as "SingleChest" (described there)

• Minecart with - Hopper

• ShulkerBox - The "Inventory" headline area is only 12, not 13 px high, unlike on the other GUIs. This needs to be quite certainly corrected. The inventory/chest slots of the Shulkerbox is 1px lower than it should be; maybe due to fix of MC-108525? Seems likely, as the SingleChest GUI might have been the template for the Shulker Box GUI; I should have realized back then that means all chest GUIs are also 1 Pixel too tall (167 vs. 166 pixel)
  Issue-Graphics: _(2)_shulkerbox.png

• SingleChest - 1px taller than the other GUIs of same size which should be all of same height.
  The "main headline area" is 1px too tall (14 vs 13 px).
  Issue-Graphics: _(1)_chest.png
  Issue-Demo-Video: chest_gui-offset-comparison.mp4

• Survival Player GUI - For consistency reasons it would be probably the best to have "Crafting" centered above the crafting grid and moved 1px up to line up with the armour slots/complete player display which are 4px apart from the GUI edges; furthermore the complete crafting area should be moved 2px to the left, so we've got our consistent 4px distance to the right edge again, not only 2px.
  Issue-Graphics: _(5)_playersurvival.png
  Fixes-Graphics: PlayerSurvival_Orig-AndAllFixes-Comparison.png
  PlayerSurvival_Fix-Comparison.png PlayerSurvival_Fix-Comparison_closeup.png

• Villager