Fix #12459 : text selection drag and drop problem.

[labordep]

I propose this fix for #12459.
It is hard to reproduce with a test (complexe mouse events) but with this fix I haven't the bug.
Thanks.

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[Ducasse]

Thanks Pierre!!!

[guillep]

Thanks Pierre! I tested this on my side and it makes the bug go away.
I'd like if you can add some comments on why the arithmetic?

If you want to write a test, I suggest to take a look at RubSelectionTest

[labordep]

Hi,
Ok good news !
I will write unit test and comment and send a new PR soon :)

[labordep]

I have rewrite some code into the RubTextEditor with unit tests. The unit tests represent the search behavior that I suppose. The selection behavior on double click is not perfect but I think this is working better. Check my tests to have a reflexion about the targeted behavior.

[Ducasse]

I do not get why suddenly we get many dispersed broken tests

[labordep]

@Ducasse I have to do something ?

[MarcusDenker]

The PR seems to lead to these tests failing:

CompletionEngineTest

• testReplaceTokenWithCaretInTheMiddleOfWordReplacesEntireWord
• testReplaceTokenWithCaretOnEndOfWordReplacesEntireWord

ProperMethodCategorizationTest

• testSetUpMethodInSUnitTestsNeedsToBeInRunningProtocol

ProtocolConventionsTest

• testProperTestProtocolIsUsed

[labordep]

Thanks @MarcusDenker, I will check theses tests

[labordep]

I have fixed a bad index computation in the completion engine and all theses tests are ok for me :

• CompletionEngineTest
• ProperMethodCategorizationTest
• ProtocolConventionsTest
• RubTextEditorTest

I'm waiting for global test checking

[labordep]

@MarcusDenker @Ducasse I don't know this system of auto verification, it appears very powerful. Apparently there is an error, how can I see where is the problem ?

[MarcusDenker]

the CI checks on 3 platforms, but the windows test runner seems to be out of disk space, so it stopped.

else it looks good.

I will open an issue for the windows test runner and put this PR on the "ready to review" status

[guillep]

I've manualy fixed the merge conflict. I'll integrate after we check it runs and I did not break anything :)