IE leaves behind color

[KatieWoe]

Test device Dell Operating System Win 10 Browser IE Problem description For https://github.com/phetsims/QA/issues/466. Fairly minor graphical issue with IE. When dragging the thermometers around, their labels on the number line can leave behind a colored line. It seems to go away when you lift up the mouse.

Visuals

Troubleshooting information:

!!!!! DO NOT EDIT !!!!! Name: ‪Number Line: Integers‬ URL: https://phet-dev.colorado.edu/html/number-line-integers/1.0.0-rc.2/phet/number-line-integers_en_phet.html Version: 1.0.0-rc.2 2020-01-21 16:03:10 UTC Features missing: touch, fullscreen Flags: pointerEnabled, msPointerEnabled, pixelRatioScaling User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; Touch; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; Tablet PC 2.0; Zoom 3.6.0; rv:11.0) like Gecko Language: en-US Window: 1536x750 Pixel Ratio: 2.5/1 WebGL: WebGL 0.94 GLSL: WebGL GLSL ES 0.94 Vendor: Microsoft (Internet Explorer) Vertex: attribs: 16 varying: 15 uniform: 512 Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32) Max viewport: 16384x16384 OES_texture_float: true Dependencies JSON: {}

[jbphet]

I spent some time on this, and I could make the problem go away by setting boundsMethod: 'accurate' on the text in the readout, but this reduced performance drastically and made dragging of the thermometers laggy, so it was clearly not a good solution. Oddly, after reverting the accurate bounds change, I could no longer get the problem to happen at all, so it was hard to continue working on it.

Since this is on IE only (which is a small proportion of our users), is not very noticeable, and the artifacts go away as soon as the thermometer is released, I'm going to propose that we not worry about this one. Assigning to @ariel-phet to see if he concurs, if so he can close.

[jbphet]

I discussed this with @ariel-phet in person, and he agreed that this isn't worth the time to pursue further. Closing.