Mesh: Stalls when creating mesh from complex objects

Issue imported from https://tracker.freecad.org/view.php?id=4346

* **Reporter:** PedjaS
* **Date submitted:** 5/17/2020
* **FreeCAD version:** 0.18
* **Category:** Feature
* **Status:** feedback
* **Tags:** #pending-forum, Mesh

# Original report text

When I try to create mesh for complex objects FreeCAD becomes non responsive. It does not break, it just seems like it spends all resources to do mesh and does not update system messages.

It just shows busy mouse icon and stops responding to anything user does.

The only way to stop it after mesh creation started is to kill application.

If I let it go for long time it eventually finishes the job.

Here are my proposals:

1. Resolve stalling by allowing FreeCAD to process system messages in appropriate place.

2. Add some kind of progress indicator. Creating mesh can take lot of time and it is advisable to provide some kind of progress update for user instead of just busy mouse icon.

I am aware that it is possible that mesh creator does not how much processing it needs to finish the job so it cannot provide accurate progress information. Accuracy is not required. More important is that user can see and follow that something is going on. Rough estimate of progress is good enough. Progress update does not even have to be in full real time. It is enough to update from time to time, as long as it keeps user informed that it works and does something.

# Steps to reproduce

I could not upload example file duo to it's size. Here is WeeTranfer link to file
https://we.tl/t-Gc9uS981JQ

Creating mesh for this object produces described issue.

# FreeCAD Info

```
OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.4 (GitTag)
Build type: Release
Branch: releases/FreeCAD-0-18
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)

```

# Other bug information

* **Priority:** normal
* **Severity:** tweak
* **Category:** Feature
* **OS: Windows 8.1**
* **Platform:** Windows
* **Updated:** 2/6/2021

# Discussion from Mantis ticket

### Comment by openBrain 2020-05-18 12:34
PedjaS : please address your issue following our [reporting guidelines](https://forum.freecadweb.org/viewtopic.php?f=3&t=5236) by opening first a topic in [our forum](https://forum.freecadweb.org/viewforum.php?f=3). Please get familiar with this [important notice before](http://forum.freecadweb.org/viewtopic.php?f=3&t=2264). Once topic is created, please post here a link to it. Thx

---

### Comment by Kunda1 2020-09-10 15:15
[Forum thread](https://forum.freecadweb.org/viewtopic.php?f=8&t=50122)

Start by reviewing the linked forum thread and the original reproduction description. The issue names no source files, tests, or entry points, and the large example file is only referenced through a WeTransfer link. Done would require a reproducible mesh-generation case and a defined responsiveness or progress-update outcome.

Written by the indexing model from the issue text.