IceTip* MUST NOT refer to UIManager

[Ducasse]

But request the application for a dialog eg.

diff

	^ diffModel ifNil: [ 
		  | diff |
		  UIManager default
			  informUser: 'Calculating diff'
			  during: [ diff := self calculateDiff ].
		  diffModel := IceTipCommitDiffModel
			               repositoryModel: self repositoryModel
			               on: diff ]

=>

diff

	^ diffModel ifNil: [ 
		  | diff |
		  self application 
			  informUser: 'Calculating diff'
			  during: [ diff := self calculateDiff ].
		  diffModel := IceTipCommitDiffModel
			               repositoryModel: self repositoryModel
			               on: diff ]

[Ducasse]

waiting for a PR to be integrated in Spec.

[Ducasse]

I started to work on this.

[Ducasse]

#1769