Incorrect ALT key behavior and no reaction on ROS Explorer window

Here's test I did on Windows XP, 7 and ReactOS for 3 different programs:

Right ALT (GR) key:

Variant A - press and hold for a while:

1. Press

2. Hold

3. Release

4. Press and release immediately

Variant B - press and release (click):

1. Press and release immediately

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Left ALT key:

Variant A - press and hold for a while:

1. Press

2. Hold

3. Release

4. Press and release immediately

Variant B - press and release (click):

1. Press and release immediately

Pressing and holding ALT keys in ReactOS does not underscore letters for menu items (which are already and always underlined even if the window is not active).
Pressing ALT keys does nothing with ROS Explorer Window (does not underline letters and the status bar does not disappear).
In ReactOS after pressing ALT key on selected window requires you to click twice in order to select another window. In Windows XP/7 only one click is required to select another window.
This gives the illusion that the interface in ReactOS is running with a delay but it is not.