.mdl-layout__drawer-button would benefit from user-select:none

.mdl-layout__tab-bar-button already has
user-select:none;

style set on it, but .mdl-layout__drawer-button does not, which means if you select some text, and then click on hamburger button to see the resulting menu it deselects your text, making it impossible to have actions in the drawer which operate on text selection (without manually overriding the user-select yourself).