Legacy Connector

Mixed 1.7.10 and 1.12.2 packs

• A library shipped for both versions (CodeChickenLib) or an API that mods of both versions shade now keeps one copy per version. Before, the two copies were merged into one, which broke every mod of the other version. In a mixed test pack, ForgeMultipart, Microblocks, ForgeRelocation, MCFrames, Logistics Pipes, MrTJPCore, Wireless Redstone, Extra Utilities, Thermal Foundation, Redstone Arsenal and Atum now load.
• Loader.isModLoaded no longer reports a mod of the other legacy version (1.12.2 Botania's Thaumcraft 6 support no longer crashes on 1.7.10's Thaumcraft 4).

Dimensions

• Mod dimensions registered while the server runs get their world on first use, as in 1.7.10. Mystcraft's instability profiling runs now, and a dimension registered at runtime with Twilight Forest's generator could be visited. Mystcraft ages and Galacticraft space stations take the same path but have not been tested yet.
• A mod that replaces the overworld's provider no longer unregisters the overworld. Mystcraft took its home dimension for dead and failed every login.

Rendering (1.7.10)

• Legacy GL matrix modes are emulated: projection (glOrtho, glFrustum, gluPerspective) and texture matrices. Galacticraft's galaxy map and catalog draw full screen in perspective instead of in the top-left corner (#37, #32).
• Thaumcraft (#84): the Thaumonomicon's frame, map and category tabs draw. The infusion matrix's runes glow instead of covering the cubes, and its crafting rays stay behind them. Plus the fixes since 0.3.0: the Thaumometer is steady, obsidian totems have their faces, sloped fluids, blue crucible water, goggles show jar contents, and banner colours are right.
• Legacy models drawn with blending keep it (additive and translucent models were drawn opaque).
• CustomOreGen's wireframes (/cogEnableDebugging) no longer crash the game, and they draw as in 1.7.10: lines in the world now use the game's line renderer, one pixel wide at any distance (#82).
• Mystcraft's linking and descriptive books draw correctly (#33).

Other fixes

• Portal Gun fires from the mouse buttons (#85; note that the mod itself refuses to place portals below y=0).
• Logistics Pipes' per-player connection checks work (NetHandlerPlayServer.netManager), HBM's key bindings no longer throw (KeyBinding.hash), and CoFH tools construct (tool effective-block fields under their legacy names).
• MineFactoryReloaded's fluids get their icons (fluid blocks link their fluid, as Forge's did; modern fluid ids are unchanged).
• Biome decoration events carry the decoration's own random number generator (Fisk's ore generation failed in Twilight Forest).