I often use the feature where I drag my window to the left or right side of the screen to make it fill half the screen. Sometimes, when my window is like that, then I click to maximize it, it doesn't maximize, but the main menu(File/Edit/etc...) and the min/max/close buttons all disappear. It doesn't happen every time, I don't know exactly what triggers it. My browser is like that now as I type this.
What causes this, and how do I fix it(besides restarting the browser)?

Note the location of my cursor.