[IconButton] IconButtons should have the same hover effect as flat buttons

[SebastianSchmidt]

• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

IconButtons should have the same hover effect as flat buttons (Example).

Current Behavior

IconButtons have no hover effect (Specification).

Steps to Reproduce

Buttons demo

Context

The difference between IconButtons and (flat) buttons is noticeable, for example, when both appear in combination in an AppBar.

Your Environment

Tech	Version
Material-UI	1.0.0-beta.39
React	16.2.0
Browser	Firefox 59, Chromium 59, Chromium 65

[SebastianSchmidt]

If this behavior is confirmed as an error, I will take care of a correction.

[oliviertassinari]

@SebastianSchmidt Two benchmarks that go against your proposition:

• https://material.angular.io/components/button/examples
• https://material.io/guidelines/components/buttons.html#buttons-toggle-buttons
  

But I believe that material-web-components are developed in tight relation with the Material Design Team. It's often safe to follow them. cc @mbrookes.

[SebastianSchmidt]

I think it would be consistent if IconButtons have a hover effect; other button-like components also have a hover effect in Material-UI (for example Menu items and Chips). However, there are other clickable components that do not have a hover effect in Material-UI (for example Tabs and Expansion panels). However, the Tabs from material-web-components have a hover effect. Material-UI may be inconsistent at this point. Perhaps it would make sense to adjust the hover effects in Material-UI so that the components behave consistently to each other.

[SebastianSchmidt]

I have created an own issue in which I will list all components with inconsistent hover effects: #10870