File search doesn't open files as preview

[dsseng]

Description

When you click (1 time) on any search result, the file is opened in edit mode, not preview one.

Reproduction Steps

1. Ctrl + Shift + F
2. Search for anything
3. Click on a result

OS and Theia version:
OS: Ubuntu 19.10
Theia: master

Diagnostics:

[akosyakov]

It should be easy to fix by passing preview: true in the opener options.

[dsseng]

@akosyakov if so, please add good first issue or another beginner-friendly label to it.

[akosyakov]

I think this line should be changed: https://github.com/maksimr/theia/blob/eabdf8800811c56435c499b84792f360616e360c/packages/search-in-workspace/src/browser/search-in-workspace-result-tree-widget.tsx#L708

But please pay attention there is some preview flag. It could be worth to test different paths leading to this code with different preview value.

cc @vince-fugnitto @elaihau @marechal-p I remember you tried to improve it last time?

[vince-fugnitto]

I thought such a behavior would not be possible without coupling search-in-workspace with editor-preview (if we want to have previewable editors which are updated upon new selections in the tree). I also think this behavior will not work if a application-developer does not explicitly depend on editor-preview.

[dsseng]

@vince-fugnitto what's about dynamical detection of required services and using preview if it's available? Sorry if it's impossible, didn't dig into those parts of code.

[akosyakov]

You don't need to add a dependency. If editor-preview is not installed then preview flag will be ignored.

[ronabet]

It should be easy to fix by passing preview: true in the opener options.
@akosyakov
I checked it and it didn`t solve the issue.