[Modal] Fix scroll jump issue

[cvara]

• I have followed (at least) the PR section of the contributing guide.

Fixes scroll jump issue that occurs when opening Modal (#18793)

@oliviertassinari I deviated from your suggested diff so that scroll is still disabled when the container is not overflowing (I also added a related test for that).

Closes #18793

[mui-pr-bot]

Details of bundle changes.

Comparing: 6fb06f9...a30251e

bundle	Size Change	Size	Gzip Change	Gzip
Menu	▼ -5 B (-0.01% )	86.9 kB	▼ -6 B (-0.02% )	26.7 kB
Drawer	▼ -5 B (-0.01% )	83 kB	▼ -5 B (-0.02% )	25.2 kB
SwipeableDrawer	▼ -5 B (-0.01% )	90.4 kB	▼ -5 B (-0.02% )	27.9 kB
@material-ui/core[umd]	▼ -5 B (-0.00% )	314 kB	▼ -4 B (-0.00% )	90.4 kB
Dialog	▼ -5 B (-0.01% )	81.3 kB	▼ -4 B (-0.02% )	25.4 kB
docs.main	▼ -5 B (-0.00% )	610 kB	▲ +4 B (0.00% )	194 kB
Popover	▼ -5 B (-0.01% )	81.3 kB	▼ -4 B (-0.02% )	25.1 kB
Select	▼ -5 B (-0.00% )	113 kB	▼ -4 B (-0.01% )	33.5 kB
TextField	▼ -5 B (-0.00% )	122 kB	▼ -4 B (-0.01% )	35.6 kB
Modal	▼ -5 B (-0.04% )	14.3 kB	▼ -3 B (-0.06% )	5 kB
TablePagination	▼ -5 B (-0.00% )	140 kB	▼ -3 B (-0.01% )	40.8 kB
@material-ui/core	▼ -5 B (-0.00% )	357 kB	--	97.4 kB
@material-ui/lab	--	175 kB	--	52.4 kB
@material-ui/styles	--	50.8 kB	--	15.3 kB
@material-ui/system	--	14.5 kB	--	4.04 kB
AppBar	--	62.5 kB	--	19.5 kB
Autocomplete	--	127 kB	--	39.8 kB
Avatar	--	63.9 kB	--	20.1 kB
AvatarGroup	--	60.9 kB	--	19.1 kB
Backdrop	--	66.4 kB	--	20.5 kB
Badge	--	64 kB	--	19.8 kB
BottomNavigation	--	61.1 kB	--	19.1 kB
BottomNavigationAction	--	74.1 kB	--	23.4 kB
Box	--	69.4 kB	--	21 kB
Breadcrumbs	--	66.7 kB	--	20.8 kB
Button	--	78.4 kB	--	23.9 kB
ButtonBase	--	72.6 kB	--	22.7 kB
ButtonGroup	--	81.8 kB	--	25 kB
Card	--	61.4 kB	--	19.1 kB
CardActionArea	--	73.7 kB	--	23.1 kB
CardActions	--	60.7 kB	--	19 kB
CardContent	--	60.7 kB	--	18.9 kB
CardHeader	--	63.7 kB	--	20 kB
CardMedia	--	61 kB	--	19.1 kB
Checkbox	--	80.6 kB	--	25.4 kB
Chip	--	81.2 kB	--	24.8 kB
CircularProgress	--	62.8 kB	--	19.7 kB
ClickAwayListener	--	3.85 kB	--	1.55 kB
Collapse	--	66.6 kB	--	20.6 kB
colorManipulator	--	3.85 kB	--	1.52 kB
Container	--	61.9 kB	--	19.3 kB
CssBaseline	--	56.2 kB	--	17.6 kB
DialogActions	--	60.8 kB	--	19 kB
DialogContent	--	60.9 kB	--	19 kB
DialogContentText	--	62.7 kB	--	19.7 kB
DialogTitle	--	63 kB	--	19.7 kB
Divider	--	61.3 kB	--	19.2 kB
docs.landing	--	52.4 kB	--	11.4 kB
ExpansionPanel	--	69.9 kB	--	21.8 kB
ExpansionPanelActions	--	60.8 kB	--	19 kB
ExpansionPanelDetails	--	60.6 kB	--	18.9 kB
ExpansionPanelSummary	--	76.8 kB	--	24.2 kB
Fab	--	75.5 kB	--	23.4 kB
Fade	--	22.2 kB	--	7.68 kB
FilledInput	--	72.1 kB	--	22.3 kB
FormControl	--	63.1 kB	--	19.6 kB
FormControlLabel	--	64.2 kB	--	20.1 kB
FormGroup	--	60.7 kB	--	19 kB
FormHelperText	--	61.9 kB	--	19.4 kB
FormLabel	--	62.1 kB	--	19.2 kB
Grid	--	63.8 kB	--	19.9 kB
GridList	--	61.2 kB	--	19.2 kB
GridListTile	--	62.4 kB	--	19.5 kB
GridListTileBar	--	61.9 kB	--	19.3 kB
Grow	--	22.8 kB	--	7.8 kB
Hidden	--	64.6 kB	--	20.2 kB
Icon	--	61.5 kB	--	19.2 kB
IconButton	--	74.8 kB	--	23.3 kB
Input	--	71.1 kB	--	22.1 kB
InputAdornment	--	63.8 kB	--	20 kB
InputBase	--	69.2 kB	--	21.6 kB
InputLabel	--	64 kB	--	19.9 kB
LinearProgress	--	64 kB	--	19.9 kB
Link	--	65.3 kB	--	20.5 kB
List	--	61 kB	--	19 kB
ListItem	--	75.8 kB	--	23.6 kB
ListItemAvatar	--	60.8 kB	--	19 kB
ListItemIcon	--	60.9 kB	--	19 kB
ListItemSecondaryAction	--	60.7 kB	--	19 kB
ListItemText	--	63.6 kB	--	19.9 kB
ListSubheader	--	61.4 kB	--	19.3 kB
MenuItem	--	76.8 kB	--	23.9 kB
MenuList	--	64.6 kB	--	20.2 kB
MobileStepper	--	66.4 kB	--	20.7 kB
NativeSelect	--	75.4 kB	--	23.7 kB
NoSsr	--	2.19 kB	--	1.03 kB
OutlinedInput	--	72.6 kB	--	22.5 kB
Paper	--	60.9 kB	--	18.9 kB
Popper	--	28.7 kB	--	10.3 kB
Portal	--	2.9 kB	--	1.3 kB
Radio	--	81.5 kB	--	25.6 kB
RadioGroup	--	61.9 kB	--	19.3 kB
Rating	--	68.7 kB	--	22 kB
RootRef	--	4.21 kB	--	1.64 kB
Skeleton	--	61.2 kB	--	19.3 kB
Slide	--	24.3 kB	--	8.3 kB
Slider	--	74.3 kB	--	23.3 kB
Snackbar	--	75.8 kB	--	23.7 kB
SnackbarContent	--	64.3 kB	--	20.2 kB
SpeedDial	--	84.7 kB	--	26.7 kB
SpeedDialAction	--	116 kB	--	36.5 kB
SpeedDialIcon	--	63.2 kB	--	19.8 kB
Step	--	61.3 kB	--	19.2 kB
StepButton	--	80.9 kB	--	25.5 kB
StepConnector	--	61.4 kB	--	19.3 kB
StepContent	--	67.7 kB	--	21.1 kB
StepIcon	--	63.3 kB	--	19.7 kB
StepLabel	--	67.3 kB	--	21.1 kB
Stepper	--	63.4 kB	--	19.9 kB
styles/createMuiTheme	--	15.4 kB	--	5.44 kB
SvgIcon	--	61.7 kB	--	19.2 kB
Switch	--	79.8 kB	--	25 kB
Tab	--	75 kB	--	23.7 kB
Table	--	61.2 kB	--	19.2 kB
TableBody	--	60.8 kB	--	19 kB
TableCell	--	62.7 kB	--	19.7 kB
TableContainer	--	60.6 kB	--	18.9 kB
TableFooter	--	60.8 kB	--	19 kB
TableHead	--	60.8 kB	--	19 kB
TableRow	--	61.2 kB	--	19.1 kB
TableSortLabel	--	76 kB	--	23.8 kB
Tabs	--	84.1 kB	--	26.5 kB
TextareaAutosize	--	5.06 kB	--	2.11 kB
ToggleButton	--	74.8 kB	--	23.6 kB
ToggleButtonGroup	--	61.9 kB	--	19.4 kB
Toolbar	--	61 kB	--	19.1 kB
Tooltip	--	99.5 kB	--	31.4 kB
TreeItem	--	72.3 kB	--	22.8 kB
TreeView	--	65 kB	--	20.4 kB
Typography	--	62.3 kB	--	19.4 kB
useAutocomplete	--	12.4 kB	--	4.62 kB
useMediaQuery	--	2.5 kB	--	1.06 kB
Zoom	--	22.3 kB	--	7.68 kB

Generated by 🚫 dangerJS against a30251e

[oliviertassinari]

@cvara Thanks for the new test case! I have tried to make the logic a bit denser, let me know :)

[cvara]

Yeah, I misread your diff, sorry. It's cleaner this way.

[oliviertassinari]

I'm happy to see this bug fixed!

[oliviertassinari]

Thank you!

[cvara]

Happy to have helped a bit :)

[oliviertassinari]

Contribution like this one x1,000 contributors, it makes a huge difference :).