5779 - Setting Display Scale Factor Changing

[David5i6]

fixes #5779

An if clause is used to return if it's not dragging the slider. MacOS and Windows, seems fixed.

Also a little comment in code and reformating for better readability.

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Please I made this change to correct a problem with Pharo 8 and Pharo 9 on Windows 10 and MacOS (not tested on Linux), but I don't have a complete vision of Morphic and Spec, Spec2.

The problem was that when movin the mouse over the slider it changes magically it's position, but not alwas. I saw that there was no "draggin" state, but instead the style of the slider is diferent and determines the state and used it to determine if slider is dragging.

I think adding a "dragging" and "dragging:" messages to set and retrieve the dragging state should be a cleaner way so I added that in a second commit.

[Ducasse]

Thanks this is uper cool that you spend your time fixing such kind of glitches. We are to used to jump over them. Thanks a lot. This is important because there is no little changes not worth.
This is because people give their energy to Pharo that it improves. So thank a lot.

[guillep]

I'd like to know, at least to keep as documentation, a couple of points.
Maybe it could make sense to add some method/class comments?

Anyways, thanks :)

[David5i6]

You're right. Due that the dragging state is now reflected on draggin variable there's no need to make the check against the borderColor.

I'm going to change it. Thanks !

[David5i6]

Re-reading the code, there some nonsense things. If mouse is down, It start dragging... but... ¿ It's possible to make the mouse down again without making it up ?

[guillep]

Thanks, I like the changes :)

[David5i6]

sorry, I detected a little very rare cases after that. I'm gouing to send a merge request again with some code guards.

[guillep]

Sure, thanks for the effort!!