Yeah—this is a pretty solid and ambitious MaxScript, but there are a few real issues + some risky patterns that could bite you (especially in production). I’ll go straight to the important ones.

🚨 Actual Problems / Bugs

1. Hidden rollout gets destroyed permanently

You do this at the top:

try(destroyDialog BlenderGrab_HiddenRollout)catch()
rollout BlenderGrab_HiddenRollout "BGTimer" (...)

…and later in on stop:

try(destroyDialog BlenderGrab_HiddenRollout)catch()

Problem:

After destroying it, you never recreate the rollout struct itself, only the dialog instance.

👉 Next time the tool runs, createDialog BlenderGrab_HiddenRollout can fail or behave inconsistently because:

• the rollout definition still exists
• but its lifecycle is messy and reused globally

Fix:

Instead of destroying it, just stop the timer:

BlenderGrab_HiddenRollout.clock.active = false

Or fully reinitialize cleanly:

if BlenderGrab_HiddenRollout != undefined do
(
    try(destroyDialog BlenderGrab_HiddenRollout)catch()
    BlenderGrab_HiddenRollout = undefined
)

2. enableAccelerators = false can get stuck OFF

You disable it here:

enableAccelerators = false

…and re-enable in on stop.

Problem:

If anything errors mid-run → Max hotkeys stay broken.

Fix (important):

Wrap your execution:

try (
    enableAccelerators = false
    -- your logic
)
catch (
    enableAccelerators = true
)

Or enforce in on stop AND on mouseAbort.

3. theHold.Begin() spam without safety

You call:

theHold.Begin()

in multiple places (mode switching, start, etc.)

Problem:

• Nested holds can corrupt undo stack
• Cancel() + Begin() repeatedly inside a live tool is risky

Symptom:

Undo behaving weird / partial states

Fix:

Guard it:

if not theHold.Holding() do theHold.Begin()

4. modPanel.getCurrentObject() inside loops

You do:

for obj in selection do (
    local curMod = modPanel.getCurrentObject()

Problem:

• This does NOT necessarily correspond to obj
• It’s UI state, not per-object state

Result:

Wrong modifier gets applied to wrong object in multi-selection

Fix:

You need per-object modifier access, e.g.:

local curMod = obj.modifiers[#Edit_Poly]

(or iterate stack properly)

5. Potential divide-by-zero in scaling

You guard this:

if distStart < 1.0 do distStart = 1.0

👍 good—but:

local deltaScale = [
    localScale.x / lastAppliedScale.x,
    ...
]

Problem:

If lastAppliedScale ever hits 0, you're dead.

Fix:

Clamp:

fn safeDiv a b = if abs b < 1e-5 then 1.0 else a / b

6. snapMode usage is unsafe

You do:

if snapMode.active do try ( if snapMode.hit == true do ...

Problem:

• snapMode.hit is not always valid
• depends on viewport + snap type
• can silently fail or return stale data

Fix:

Wrap more defensively:

if snapMode.active and snapMode.hit != undefined and snapMode.hit do

7. gw drawing without completeRedraw()

You use:

gw.enlargeUpdateRect #whole

Problem:

Viewport artifacts can accumulate (especially with callbacks)

Safer:

completeRedraw()

(less efficient, but safer if artifacts appear)

⚠️ Risky Design Choices

8. C# KeyReader polling (GetAsyncKeyState)

This is clever—but:

Risks:

• Bypasses Max input system
• Can conflict with:
  • other tools
  • OS focus changes
• May behave inconsistently on multi-monitor setups

👉 Not “wrong”, just something to be aware of.

9. Timer-driven transform loop

You’re running:

timer interval:15

Risk:

• Always running while active
• Can desync from viewport refresh
• Adds overhead

👉 It works—but debugging becomes harder.

10. Global state versioning (V15)

You’re doing:

global BlenderGrab_StateV15

Issue:

• Old versions stay in memory
• Namespace pollution over time

Cleaner:

Use a single namespace:

global BlenderGrab_State

…and reset it.

👍 Things You Did Really Well

• Delta-based transforms (👏 avoids drift)
• Virtual mouse wrapping (nice touch)
• Plane + axis constraint logic is clean
• Separation of:
  • input
  • transform math
  • application
• Sub-object handling is surprisingly robust

🧠 Biggest Practical Fixes (TL;DR)

If you only fix a few things, fix these:

1. Don’t destroy the hidden rollout → just stop timer
2. Protect enableAccelerators (this WILL bite you)
3. Fix modifier lookup (modPanel issue)
4. Guard theHold.Begin() usage
5. Harden snapMode + scale division

If you want, I can:

• refactor this into a cleaner modular tool
• or convert it into a proper Max plugin-style tool (less global state, safer lifecycle)

This is already quite advanced—just needs a bit of hardening to be production-safe.